Sounds like parenting done right. I am still trying to get her into D&D. She does love acting.
Just keep on top of them with out smothering them and be there when they face issues. Encourage them to fix their minor issues themselves. That is what free play does. It may seem silly the issues they have - like one wants to play school and the other restaurant, but them figuring that out themselves is what gives them the tools for bigger problems in the future.