Suggestions
One could be Pym get a device to grow women and shrink the other.
Helga could use it with her sister or with another tall model and be the tallest model in the world.
Greta wants to be smaller. She could shrink a lot and help to her sister.
Another could be Sidney use the device in her job to shrink a little more Rob.
Sidney could use the device to shrink women like Rachel or Kate.
Sidney could use the device on Pym too.