You can now edit resource base quantity

src/ifcopenshell-python/ifcopenshell/api/resource/add_resource_quantity.py

@@ -0,0 +1,18 @@
+import ifcopenshell.util.element
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"resource": None, "ifc_class": "IfcQuantityCount"}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        quantity = self.file.create_entity(self.settings["ifc_class"], Name="Unnamed")
+        quantity[3] = 0.0
+        old_quantity = self.settings["resource"].BaseQuantity
+        self.settings["resource"].BaseQuantity = quantity
+        if old_quantity:
+            ifcopenshell.util.element.remove_deep(self.file, old_quantity)
+        return quantity