Fondant decorations on top of buttercream?

[MerryMarigold]

Will this work?

Dd's favourite is vanilla buttercream, so I want to cover her cake in it. However, she likes all things pretty and playdough, so I was going to get her to make some of her own decorations, little flowers etc. to stick on the cake. Will they go all soft and sticky when they touch the buttercream and absorb water? How long do I have eg. if I put them on top of the buttercream an hour before, will they be safe? Thanks, super bakers.

PS. Just to clarify: the pretty bits will not be made out of playdough, but will be made out of fondant.

I've done this and it was fine. I used flower paste though, not fondant. If you make them on advance they go hard, so should be fine by the time you put them on the cake. Fondant is stickier, but I'd have thought you'd be OK with it.

Ok, I can buy some sugar paste. Thankyou. How long where they on the buttercream for?

Probably about 5 hours or so before I served it.

Thank you. That will be plenty of time I think.