I thought I read somewhere that RI decorations that are placed on buttercream will "melt" (i.e. lose their shape). Am I remembering correctly? I wanted to put some RI snowflakes directly on a BC cake, but they will be sitting on the BC for at least 9 hours before eating. Is this a bad idea? What do you recommend I do? (i.e. pipe BC snowflakes instead, etc.)

They should be fine. Don't worry!

Thanks! I'm so glad to hear that. Also, I forgot to ask...how do you attach the snowflakes to wires?

That is an "old wives tale" that just will not die!
It is in the making of royal that no grease can come in contact w/it. Once ri is properly made (and especially once dried) there is little, if any problems w/it.
Here are a couple of examples:

Wow...very pretty, kakeladi! Thank you for also for responding. It's good to know that it just an old wives' tale! I was wondering...can you put the RI decorations on indefinitely? Or is their a time frame that I should consider? Or is this part of the old wives' tale, too?

The thinner the deco the more chance there might be a problem. I would hold off applying what I could that is RI until the last minute but I have never had a problem Sometime some item might soften a bit but it will not melt, loose their shape or turn into a puddle for sure.