When I create a container with different types of objects, the objects will always be created at the source point of the parent object like you said.
The solution that I do is:
Container ("Father", "Son1", "Son2")
When the object "Father" is created:
Set Son1.X = Pai.X + 20
Set Son2.Y = Pai.Y + 100
I think it's not the best solution for that, but it works for me. Good luck.