Does a 10" round fit on a 12" petal? Or will the 10" overlap the bits between the "petals"? I'm looking to do a 6, 8, 10, 12" but the bride would like a petal shape on the bottom tier. I'd like to avoid a 15" if possible because it will be too much cake, but she would like 4 tiers. Thanks!

I just tested it with my pans. I have the Wilton petals and the 10" round fit fine on the 12" petal. Not sure if this matters or not, but I will say the round just fit inside the petals...the petals were all that was bigger that than the round (does that make sense?). 

Yes, so the round 10" fits snug on the round centre part of the 12" petal, only the scalloped parts protruding. Thank you!