I am doing my first wedding cake for a May wedding.  The bride provided a picture of the cake she wants and it is a 4 tier cake with 12,10,8 and 6 inch tiers, serving 130.  Her guest list is 120.  I can't post a picture of it but it is all buttercream.  Bottom or 1st tier is Rosettes, second tier plain with a ribbon, third tier Rosettes, and top tier is quilted with dragees in the intersections.  All tiers are something I have done before as single cakes but I have never stacked them.  I have experience stacking up to 3 layers, but those cakes were done in fondant. 

How do I stack buttercream cakes (especially the Rosettes) without messing them up.  Do I stack them and then do the Rosettes?  If so, how do I transport the cake.  Should I pipe the Rosettes onsite?  I can and will practice on dummies, but thought I would ask to see if someone already has experience with this.

Ok - Answering my own question.  I think after reading some previously asked questions that I should stack the cake on site.  My plan is to not put the rosettes on the tops of the cakes until my layers are stacked.  I can fix fingerprints or holes in plain buttercream, but the rosettes would be difficult to repair.  I normally make rosette cakes with noncrusting buttercream because I like the taste better, but I will make this one with a crusting buttercream. 

Still going to do this with dummy cakes to make sure my plan works.

Thanks to all of you who have gone before me.  Awesome site.

SPS is your answer for stacking/support