diff --git a/README.md b/README.md
index 16a86ba..89c7d05 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,8 @@ Note that closure_tree only supports ActiveRecord 7.2 and later, and has test co
 
     Make sure you check out the [large number of options](#available-options) that `has_closure_tree` accepts.
 
+    **Note:** The `acts_as_tree` alias is only created if your model doesn't already have a method with that name. This prevents conflicts with other gems like the original `acts_as_tree` gem.
+
     **IMPORTANT: Make sure you add `has_closure_tree` _after_ `attr_accessible` and
     `self.table_name =` lines in your model.**
 
@@ -156,10 +158,10 @@ Then:
 
 ```ruby
 grandparent.self_and_descendants.collect(&:name)
-=> ["Grandparent", "Parent", "First Child", "Second Child", "Third Child", "Fourth Child"]
+#=> ["Grandparent", "Parent", "First Child", "Second Child", "Third Child", "Fourth Child"]
 
 child1.ancestry_path
-=> ["Grandparent", "Parent", "First Child"]
+#=> ["Grandparent", "Parent", "First Child"]
 ```
 
 ### find_or_create_by_path
@@ -204,19 +206,16 @@ d = Tag.find_or_create_by_path %w[a b c d]
 h = Tag.find_or_create_by_path %w[e f g h]
 e = h.root
 d.add_child(e) # "d.children << e" would work too, of course
-h.ancestry_path
-=> ["a", "b", "c", "d", "e", "f", "g", "h"]
+h.ancestry_path #=> ["a", "b", "c", "d", "e", "f", "g", "h"]
 ```
 
 When it is more convenient to simply change the `parent_id` of a node directly (for example, when dealing with a form `<select>`), closure_tree will handle the necessary changes automatically when the record is saved:
 
 ```ruby
 j = Tag.find 102
-j.self_and_ancestor_ids
-=> [102, 87, 77]
+j.self_and_ancestor_ids #=> [102, 87, 77]
 j.update parent_id: 96
-j.self_and_ancestor_ids
-=> [102, 96, 95, 78]
+j.self_and_ancestor_ids #=> [102, 96, 95, 78]
 ```
 
 ### Nested hashes
@@ -233,17 +232,13 @@ c1 = d1.parent
 d2 = b.find_or_create_by_path %w(c2 d2)
 c2 = d2.parent
 
-Tag.hash_tree
-=> {a => {b => {c1 => {d1 => {}}, c2 => {d2 => {}}}, b2 => {}}}
+Tag.hash_tree #=> {a => {b => {c1 => {d1 => {}}, c2 => {d2 => {}}}, b2 => {}}}
 
-Tag.hash_tree(:limit_depth => 2)
-=> {a => {b => {}, b2 => {}}}
+Tag.hash_tree(:limit_depth => 2) #=> {a => {b => {}, b2 => {}}}
 
-b.hash_tree
-=> {b => {c1 => {d1 => {}}, c2 => {d2 => {}}}}
+b.hash_tree #=> {b => {c1 => {d1 => {}}, c2 => {d2 => {}}}}
 
-b.hash_tree(:limit_depth => 2)
-=> {b => {c1 => {}, c2 => {}}}
+b.hash_tree(:limit_depth => 2) #=> {b => {c1 => {}, c2 => {}}}
 ```
 
 **If your tree is large (or might become so), use :limit_depth.**
@@ -477,20 +472,16 @@ c = OrderedTag.create(name: 'c')
 # We have to call 'root.reload.children' because root won't be in sync with the database otherwise:
 
 a.append_sibling(b)
-root.reload.children.pluck(:name)
-=> ["a", "b"]
+root.reload.children.pluck(:name) #=> ["a", "b"]
 
 a.prepend_sibling(b)
-root.reload.children.pluck(:name)
-=> ["b", "a"]
+root.reload.children.pluck(:name) #=> ["b", "a"]
 
 a.append_sibling(c)
-root.reload.children.pluck(:name)
-=> ["b", "a", "c"]
+root.reload.children.pluck(:name) #=> ["b", "a", "c"]
 
 b.append_sibling(c)
-root.reload.children.pluck(:name)
-=> ["b", "c", "a"]
+root.reload.children.pluck(:name) #=> ["b", "c", "a"]
 ```
 
 ### Ordering Roots
diff --git a/lib/closure_tree.rb b/lib/closure_tree.rb
index 728ee79..5bfcbc5 100644
--- a/lib/closure_tree.rb
+++ b/lib/closure_tree.rb
@@ -9,11 +9,16 @@
 
 module ClosureTree
   def self.configure
-    ActiveSupport::Deprecation.new.warn(
-      'ClosureTree.configure is deprecated and will be removed in a future version. ' \
-      'Configuration is no longer needed.'
-    )
-    yield if block_given?
+    if block_given?
+      # Create a temporary configuration object to capture deprecated settings
+      config = Configuration.new
+      yield config
+    else
+      ActiveSupport::Deprecation.new.warn(
+        'ClosureTree.configure is deprecated and will be removed in a future version. ' \
+        'Configuration is no longer needed.'
+      )
+    end
   end
 end
 
diff --git a/lib/closure_tree/association_setup.rb b/lib/closure_tree/association_setup.rb
new file mode 100644
index 0000000..3b5a379
--- /dev/null
+++ b/lib/closure_tree/association_setup.rb
@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require 'active_support/concern'
+
+module ClosureTree
+  # This concern sets up the ActiveRecord associations after all other modules are included.
+  # It must be included last to ensure that HierarchyMaintenance callbacks are already set up.
+  module AssociationSetup
+    extend ActiveSupport::Concern
+
+    included do
+      belongs_to :parent, nil,
+                 class_name: _ct.model_class.to_s,
+                 foreign_key: _ct.parent_column_name,
+                 inverse_of: :children,
+                 touch: _ct.options[:touch],
+                 optional: true
+
+      order_by_generations = -> { Arel.sql("#{_ct.quoted_hierarchy_table_name}.generations ASC") }
+
+      has_many :children, *_ct.has_many_order_with_option, class_name: _ct.model_class.to_s,
+                                                           foreign_key: _ct.parent_column_name,
+                                                           dependent: _ct.options[:dependent],
+                                                           inverse_of: :parent do
+        # We have to redefine hash_tree because the activerecord relation is already scoped to parent_id.
+        def hash_tree(options = {})
+          # we want limit_depth + 1 because we don't do self_and_descendants.
+          limit_depth = options[:limit_depth]
+          _ct.hash_tree(@association.owner.descendants, limit_depth ? limit_depth + 1 : nil)
+        end
+      end
+
+      has_many :ancestor_hierarchies, *_ct.has_many_order_without_option(order_by_generations),
+               class_name: _ct.hierarchy_class_name,
+               foreign_key: 'descendant_id'
+
+      has_many :self_and_ancestors, *_ct.has_many_order_without_option(order_by_generations),
+               through: :ancestor_hierarchies,
+               source: :ancestor
+
+      has_many :descendant_hierarchies, *_ct.has_many_order_without_option(order_by_generations),
+               class_name: _ct.hierarchy_class_name,
+               foreign_key: 'ancestor_id'
+
+      has_many :self_and_descendants, *_ct.has_many_order_with_option(order_by_generations),
+               through: :descendant_hierarchies,
+               source: :descendant
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/closure_tree/configuration.rb b/lib/closure_tree/configuration.rb
new file mode 100644
index 0000000..b81bc4d
--- /dev/null
+++ b/lib/closure_tree/configuration.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module ClosureTree
+  # Minimal configuration class to handle deprecated options
+  class Configuration
+    def database_less=(_value)
+      ActiveSupport::Deprecation.new.warn(
+        'ClosureTree.configure { |config| config.database_less = true } is deprecated ' \
+        'and will be removed in v10.0.0. The database_less option is no longer needed ' \
+        'for modern deployment practices. Remove this configuration from your initializer.'
+      )
+      # Ignore the value - this is a no-op for backward compatibility
+    end
+
+    def database_less?
+      false # Always return false since this option does nothing
+    end
+
+    # Keep the old method name for backward compatibility
+    alias database_less database_less?
+  end
+end
diff --git a/lib/closure_tree/has_closure_tree.rb b/lib/closure_tree/has_closure_tree.rb
index ee6db3a..5550cc7 100644
--- a/lib/closure_tree/has_closure_tree.rb
+++ b/lib/closure_tree/has_closure_tree.rb
@@ -25,7 +25,8 @@ def has_closure_tree(options = {})
       class_attribute :hierarchy_class
       self.hierarchy_class = _ct.hierarchy_class_for_model
 
-      # tests fail if you include Model before HierarchyMaintenance wtf
+      # Include modules - HierarchyMaintenance provides callbacks that Model associations depend on
+      # The order is maintained for consistency, but associations are now set up after all includes
       include ClosureTree::HierarchyMaintenance
       include ClosureTree::Model
       include ClosureTree::Finders
@@ -35,9 +36,13 @@ def has_closure_tree(options = {})
       include ClosureTree::DeterministicOrdering if _ct.order_option?
       include ClosureTree::NumericDeterministicOrdering if _ct.order_is_numeric?
 
+      # Include AssociationSetup last to ensure all dependencies are ready
+      include ClosureTree::AssociationSetup
+
       connection_pool.release_connection
     end
 
-    alias acts_as_tree has_closure_tree
+    # Only alias acts_as_tree if it's not already defined (to avoid conflicts with other gems)
+    alias acts_as_tree has_closure_tree unless method_defined?(:acts_as_tree)
   end
 end
diff --git a/lib/closure_tree/model.rb b/lib/closure_tree/model.rb
index dee315c..98ba50f 100644
--- a/lib/closure_tree/model.rb
+++ b/lib/closure_tree/model.rb
@@ -6,45 +6,6 @@ module ClosureTree
   module Model
     extend ActiveSupport::Concern
 
-    included do
-      belongs_to :parent, nil,
-                 class_name: _ct.model_class.to_s,
-                 foreign_key: _ct.parent_column_name,
-                 inverse_of: :children,
-                 touch: _ct.options[:touch],
-                 optional: true
-
-      order_by_generations = -> { Arel.sql("#{_ct.quoted_hierarchy_table_name}.generations ASC") }
-
-      has_many :children, *_ct.has_many_order_with_option, class_name: _ct.model_class.to_s,
-                                                           foreign_key: _ct.parent_column_name,
-                                                           dependent: _ct.options[:dependent],
-                                                           inverse_of: :parent do
-        # We have to redefine hash_tree because the activerecord relation is already scoped to parent_id.
-        def hash_tree(options = {})
-          # we want limit_depth + 1 because we don't do self_and_descendants.
-          limit_depth = options[:limit_depth]
-          _ct.hash_tree(@association.owner.descendants, limit_depth ? limit_depth + 1 : nil)
-        end
-      end
-
-      has_many :ancestor_hierarchies, *_ct.has_many_order_without_option(order_by_generations),
-               class_name: _ct.hierarchy_class_name,
-               foreign_key: 'descendant_id'
-
-      has_many :self_and_ancestors, *_ct.has_many_order_without_option(order_by_generations),
-               through: :ancestor_hierarchies,
-               source: :ancestor
-
-      has_many :descendant_hierarchies, *_ct.has_many_order_without_option(order_by_generations),
-               class_name: _ct.hierarchy_class_name,
-               foreign_key: 'ancestor_id'
-
-      has_many :self_and_descendants, *_ct.has_many_order_with_option(order_by_generations),
-               through: :descendant_hierarchies,
-               source: :descendant
-    end
-
     # Delegate to the Support instance on the class:
     def _ct
       self.class._ct