You can now copy cost values from one cost item to another

src/ifcopenshell-python/ifcopenshell/api/cost/copy_cost_item_values.py

@@ -0,0 +1,17 @@
+import ifcopenshell.util.element
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"source": None, "destination": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        for cost_value in self.settings["destination"].CostValues or []:
+            ifcopenshell.api.run("cost.remove_cost_item_value", self.file, cost_value=cost_value)
+        copied_cost_values = []
+        for cost_value in self.settings["source"].CostValues or []:
+            copied_cost_values.append(ifcopenshell.util.element.copy_deep(self.file, cost_value))
+        self.settings["destination"].CostValues = copied_cost_values