Can I put buttercream cutouts (stars) on a fondant covered cake? Will they stay on the cake or will the fondant become mushy where they are placed? Will the stars sag or fall off? If this would work, what woul I use to stick the stars to the fondant? Water?

OR... can you put rolled buttercream star cutouts on a cake covered with buttercream? Will this hold up?

I want to make an oval 2 - layer cake covered with buttercream and then put fondant stars on the top and sides of the cake. I need an answer quickly as I have to make this for the weekend. I have not been able to find a definite answer to my question.

unless you are using rolled buttercream, i see no way to cut out a buttercream shape.

maybe doing a FBCT, freezing, cutting, freezing again, then placing on the cake?

buttercream on fondant will hold up. i do it all the time.