any kind of fruit you add to cake mix should be coated in flour first
it makes it stay stable and not sink

you could always deliberatly place the pineapple in the bottom of the
cake pans with a little brown suger and butter and make them in to
upside down pineapple cupcakes

maybe use pineapple rings and a cherry in the middle of the ring ....
just for something a little different

Tessa