So I've only made three wedding cakes and I've had the same problem with all three. I NEVER have this problem with other cakes (even stacked). They look fine to begin with and then they begin to buldge and sink a bit. Here they are- maybe you can help?? First two are buttercream and last one is mmf.

Ugg, won't let me upload the other two pictures. I'll post and try again.

second cake

Some ideas that I've heard on here before to help with this type of problem are:
1. Make sure the frosting dam between layers is a stiffer consistency frosting
2. Make sure to press you layers gently together to try to prevent future settling/buldging
3. Torte and fill you cakes and let them sit overnight before frosting them so they have a chance to settle and minimize buldging.
I learned all those ideas from this site and I'm sure there some more tips out there. Hope this helps.
Kate

Cake from last night.

There's also an article about this very issue in the Articles section that is very helpful. I had the same thing happen with my last cake, for the first time--fortunately it was a practice cake...!

Are you using dowels? If so, maybe you can add a few more for extra support. Or, maybe you are cutting them a little too short?

Sorry, I'm not much help.

They were buldging before I put the dowels in. I read the article (thanks for pointing me in that directon) and I think I need to try again and let it sit over night. Do you crumbcoat first? Or wrap in saran wrap or something? I just worry about the layers drying out after filling. I'm making a cake for my daughter's birthday- I'll do it tiered to experiment.

Some other (maybe) helpful insight:
I use 3 inch pans and torte my cakes
I bake with doctored cake mixes

The cakes do need to settle and as you all use box mixes I tried this and it is the only way of getting that soft soft texture but I am afraid my children would not eat it. After having scratchj cakes all their lives a box was OUT OF THE QUESTION any how what I am saying is the lovely soft texture sinks and this is with out even coating it. TOOOO SOFT, Good luck

Definitely let the stacked cake sit for a while so it settles. I have that problem too sometimes. On the last cake I put the second layer on after filling it, then pushed it down a bit, and let it sit over night. Then crumb coat, let it sit. Then final coating.

I would maybe revise the filling recipe. It might need more gelatin, or something to make the filling stiffer. I scrapped a filling recipe I had for that reason. I could get the cake to stay together fine, but when it was sliced, the filling gushed a little and the cake slices were falling apart a little which was less than pretty. Just keep experimenting. You'll find what works!

Another helpful tip...do not overfill with your filling. I have also had this issue. It was very easily corrected by piping a still dam and A LOT less filling. Push your layers together and then let sit for a while or overnight before frosting.

From the looks of your pictures...I think the tiers might have too much filling. This is how my cake looked too!

Good luck on your next one...we all have to live and learn!

Maybe you need a "stiffer" cake recipe. This cake could be to moist and thus can't hold the weight.