I am doing a three tiered wedding cake in a cornflower blue and have decided to cover in buttercream instead of fondant due to the color.

The two bottom layers will be dummy cakes, while the top tier will be real cake. I'm wondering how to stack the cakes together?

If I'm using buttercream, I'm worried that when I put the second and third tiers on, the butter cream will squish out the between the layers.

How to I get the top, real cake, layer to be stable ontop of the styrofoam dummys? Do I need to use dowels?

Also, I've read that buttercream will harden after a few days, but I need to insert wire decorations into them. Will that affect the buttercream?

Any suggestions? Thanks!

If anyone else out there is wondering the same thing I did, which I never got an answer to, here's what I did:

First I saran wrapped the dummy cakes. Then I frosted them in royal icing and let it harden. About three days before the event I frosted over the royal icing in buttercream. The buttercream hardened enough that I simply put some frosting between all the layers and they stuck just fine. I didn't use any dowels.

I was still able to insert my gumpaste twigs into the styrofoam without issue. When I put the twigs into the real cake (top tier) the buttercream didn't cause any bleeding.

Here's a link to the cake, http://www.cakecentral.com/cake-photo_1808945.html