I was wondering if anyone could tell me, when stacking dummies, so you use SPS, cake boards or dowels? Or if anyone could describe the process for Dummies, that would be soooo helpful, as I have never used them before. TIA

You can just stack the dummies on top of each other. I use piping gel to stick them together. Some people use royal icing. They do not need anything else.

Your question was asked today... this may help:
http://cakecentral.com/cake-decorating-ftopict-729499.html

If you're using styrofoam dummies, you shouldn't need any support other than the dummy below. The foam dummies are so lightweight (even when covered with fondant), that you don't need anything else. I usually stick them together with a little royal icing and end up with a very solid "cake". Hope that helps!

Great thank you guys, oh, one more question, how long do they last? I have a cake to do for an auction and I need to supply pictures for the catalog by October, but the Auction isnt until January. Will it last if I keep it wrapped and covered, refrigerated perhaps?

Just cover the dummie cake lightly with a plastic bag to keep the dust off. Place it in a cool dry area. Not the fridge. If you are using coloured gumpaste or fondant decorations mix in 1 tsp baking soda per 1 pound. This will help to keep the colour. Use a dark plastic bag if fondant is coloured.
The cake can last for years if stored correctly.

Excellent!!! Thanks dsilvest!!

A little off topic, but how do I attach gumpaste flowers to the cake dummies? Can I just poke them into the fondant?

I would think that you could just stick them in, but hopefully someone will answer that knows for sure. I had another question as well, do people cover their dummies with saran wrap then BC them then Fondant? Also is a 5" dummy better than a 4"?

Some people saran wrap, some don't. In my experience, the saran wrap doesn't really make any difference when taking off dried royal icing or fondant.

I would not use buttercream underneath, as it is perishable, but maybe others do? I prefer to use a small amount of piping gel to get the fondant to stick.

Thank you! That saves me money as well!

thank you!!