Oh, some things for you and others to know: The main difference between a stage working as final destination and wifi room is the modeldata2. For a wifi room, the contents of modeldata2 don't exist. Final destination needs the modeldata2, if doesn't exist, then crashes. So to make a stage compatible with both, you have to:
1- Have a modeldata2 with a model inside (I usually use an empty model, I call it static)
2- Have all the contents of the stage in modeldata1 and modeldata101, those are shared by both types of stages.
Hope this helps many people