Will a piece of fondant that has been made ahead of time and is dry, get soft again when you put it on something that is covered in buttercream? Like the top part of a graduation cap. Also if you make the tassel out of buttercream, will it start drooping on that side? Thanks for your help, Marilyn

It depends on how 'wet' the icing is. The fondant will soften over time, but it won't just instantly start melting. If the buttercream is crusting, it may not soften much at all.

Try adding crisco to the fondant if they does not work then the fondant is too dry to work with. I would make the tassel out of fondant buttercream will not hold up as well for the tassel.