diff --git a/rust/kcl-lib/src/execution/exec_ast.rs b/rust/kcl-lib/src/execution/exec_ast.rs
index fcbea5f0189..420dfee771f 100644
--- a/rust/kcl-lib/src/execution/exec_ast.rs
+++ b/rust/kcl-lib/src/execution/exec_ast.rs
@@ -753,7 +753,7 @@ impl ExecutorContext {
                     if let ModulePath::Std { value: std_path } = &exec_state.mod_local.path {
                         let (func, props) = crate::std::std_fn(std_path, statement_kind.expect_name());
                         KclValue::Function {
-                            value: Box::new(FunctionSource::rust(func, function_expression.clone(), props, attrs)),
+                            value: vec![FunctionSource::rust(func, function_expression.clone(), props, attrs)],
                             meta: vec![metadata.to_owned()],
                         }
                     } else {
@@ -767,11 +767,11 @@ impl ExecutorContext {
                     // over variables. Variables defined lexically later shouldn't
                     // be available to the function body.
                     KclValue::Function {
-                        value: Box::new(FunctionSource::kcl(
+                        value: vec![FunctionSource::kcl(
                             function_expression.clone(),
                             exec_state.mut_stack().snapshot(),
                             matches!(&exec_state.mod_local.path, ModulePath::Std { .. }),
-                        )),
+                        )],
                         meta: vec![metadata.to_owned()],
                     }
                 }
diff --git a/rust/kcl-lib/src/execution/fn_call.rs b/rust/kcl-lib/src/execution/fn_call.rs
index 687579d1a4d..45cc4be2915 100644
--- a/rust/kcl-lib/src/execution/fn_call.rs
+++ b/rust/kcl-lib/src/execution/fn_call.rs
@@ -174,7 +174,8 @@ impl Node<CallExpressionKw> {
 
         let args = Args::new(fn_args, unlabeled, callsite, exec_state, ctx.clone());
 
-        let return_value = fn_src
+        // TODO check functions
+        let return_value = fn_src[0]
             .call_kw(Some(fn_name.to_string()), exec_state, ctx, args, callsite)
             .await
             .map_err(|e| {
diff --git a/rust/kcl-lib/src/execution/kcl_value.rs b/rust/kcl-lib/src/execution/kcl_value.rs
index 1c0a9555ad8..373c97dc137 100644
--- a/rust/kcl-lib/src/execution/kcl_value.rs
+++ b/rust/kcl-lib/src/execution/kcl_value.rs
@@ -87,7 +87,8 @@ pub enum KclValue {
     Function {
         #[serde(serialize_with = "function_value_stub")]
         #[ts(type = "null")]
-        value: Box<FunctionSource>,
+        // usize is the epoch at which the function was added to the value
+        value: Vec<(usize, FunctionSource)>,
         #[serde(skip)]
         meta: Vec<Metadata>,
     },
@@ -111,7 +112,7 @@ pub enum KclValue {
     },
 }
 
-fn function_value_stub<S>(_value: &FunctionSource, serializer: S) -> Result<S::Ok, S::Error>
+fn function_value_stub<S>(_value: &Vec<(usize, FunctionSource)>, serializer: S) -> Result<S::Ok, S::Error>
 where
     S: serde::Serializer,
 {
@@ -474,13 +475,16 @@ impl KclValue {
 
     pub(crate) fn map_env_ref(&self, old_env: usize, new_env: usize) -> Self {
         let mut result = self.clone();
-        if let KclValue::Function { ref mut value, .. } = result
-            && let FunctionSource {
-                body: FunctionBody::Kcl(memory),
-                ..
-            } = &mut **value
-        {
-            memory.replace_env(old_env, new_env);
+        if let KclValue::Function { ref mut value, .. } = result {
+            for value in value {
+                if let FunctionSource {
+                    body: FunctionBody::Kcl(memory),
+                    ..
+                } = &mut value.1
+                {
+                    memory.replace_env(old_env, new_env);
+                }
+            }
         }
 
         result
@@ -702,8 +706,8 @@ impl KclValue {
         }
     }
 
-    /// If this value is of type function, return it.
-    pub fn as_function(&self) -> Option<&FunctionSource> {
+    /// If this value is of type function, return the function definitions.
+    pub fn as_function(&self) -> Option<&[FunctionSource]> {
         match self {
             KclValue::Function { value, .. } => Some(value),
             _ => None,
diff --git a/rust/kcl-lib/src/execution/memory.rs b/rust/kcl-lib/src/execution/memory.rs
index 5a7913099c2..68652e9ceff 100644
--- a/rust/kcl-lib/src/execution/memory.rs
+++ b/rust/kcl-lib/src/execution/memory.rs
@@ -628,7 +628,28 @@ impl Stack {
     /// Add a value to the program memory (in the current scope). The value must not already exist.
     pub fn add(&mut self, key: String, value: KclValue, source_range: SourceRange) -> Result<(), KclError> {
         let env = self.memory.get_env(self.current_env.index());
+
         if env.contains_key(&key) {
+            if let KclValue::Function { value: new_fn, .. } = value {
+                if Some(true)
+                    == env.update(
+                        &key,
+                        move |value, epoch| {
+                            match value {
+                                KclValue::Function { value, ..} => {
+                                    value.extend(new_fn.into_iter().map(|f| (epoch, f.1)));
+                                    true
+                                }
+                                _ => false,
+                            }
+                        },
+                        self.memory.epoch.load(Ordering::Relaxed),
+                        self.id,
+                    )
+                {
+                    return Ok(());
+                }
+            }
             return Err(KclError::new_value_already_defined(KclErrorDetails::new(
                 format!("Cannot redefine `{key}`"),
                 vec![source_range],
@@ -979,13 +1000,19 @@ mod env {
                 .ok_or(self.parent)
         }
 
-        pub(super) fn update(&self, key: &str, f: impl Fn(&mut KclValue, usize), epoch: usize, owner: usize) {
+        pub(super) fn update<T>(
+            &self,
+            key: &str,
+            f: impl FnOnce(&mut KclValue, usize) -> T,
+            epoch: usize,
+            owner: usize,
+        ) -> Option<T> {
             let Some((_, value)) = self.get_mut_bindings(owner).get_mut(key) else {
                 debug_assert!(false, "Missing memory entry for {key}");
-                return;
+                return None;
             };
 
-            f(value, epoch);
+            Some(f(value, epoch))
         }
 
         pub(super) fn parent(&self) -> Option<EnvironmentRef> {
@@ -1291,11 +1318,11 @@ mod test {
         mem.add(
             "f".to_owned(),
             KclValue::Function {
-                value: Box::new(FunctionSource::kcl(
+                value: vec![(0, FunctionSource::kcl(
                     crate::parsing::ast::types::FunctionExpression::dummy(),
                     sn2,
                     false,
-                )),
+                ))],
                 meta: Vec::new(),
             },
             sr(),
@@ -1306,7 +1333,7 @@ mod test {
         assert_get(mem, "a", 1);
         assert_get(mem, "b", 2);
         match mem.get("f", SourceRange::default()).unwrap() {
-            KclValue::Function { value, .. } => match &**value {
+            KclValue::Function { value, .. } if value.len() == 1 => match &value[0].1 {
                 FunctionSource {
                     body: crate::execution::kcl_value::FunctionBody::Kcl(memory),
                     ..
diff --git a/rust/kcl-lib/src/lsp/kcl/mod.rs b/rust/kcl-lib/src/lsp/kcl/mod.rs
index a8543d1677a..a30fe3f4a32 100644
--- a/rust/kcl-lib/src/lsp/kcl/mod.rs
+++ b/rust/kcl-lib/src/lsp/kcl/mod.rs
@@ -1044,9 +1044,10 @@ impl LanguageServer for Backend {
                 let (sig, docs) = if let Some(Some(result)) = with_cached_var(&name, |value| {
                     match value {
                         // User-defined function
-                        KclValue::Function { value, .. } if !value.is_std => {
+                        KclValue::Function { value, .. } if !value[0].1.is_std => {
+                            let sigs: Vec<_> = value.iter().map(|v| v.1.ast.signature()).collect();
                             // TODO get docs from comments
-                            Some((value.ast.signature(), ""))
+                            Some((sigs.join("\n---\n"), ""))
                         }
                         _ => None,
                     }
diff --git a/rust/kcl-lib/src/std/args.rs b/rust/kcl-lib/src/std/args.rs
index 410ca8dced1..df0db8fcdfc 100644
--- a/rust/kcl-lib/src/std/args.rs
+++ b/rust/kcl-lib/src/std/args.rs
@@ -1167,7 +1167,11 @@ impl<'a> FromKclValue<'a> for Box<Solid> {
 
 impl<'a> FromKclValue<'a> for FunctionSource {
     fn from_kcl_val(arg: &'a KclValue) -> Option<Self> {
-        arg.as_function().cloned()
+        let f = arg.as_function()?;
+        if f.len() != 1 {
+            return None;
+        }
+        Some(f[0].clone())
     }
 }