I'm sure this has been on here a zillion times but how do I adapt a yellow mix for stacking layers? I baked the layers from scratch and they are way to light and crumbly for what I need so now in a pinch I need to doctor a cake mix. Thanks for the help and so sorry for the repetition.

YOu can use any kind of cake you want for a stacked cake because it has no bearing on the stacking. The cake is not what is supporting the upper tiers. Your support system is. You can make a bottom tier out of jello and with the proper support system, you can put a 5-tier cake on top of the jello and it will stand just fine. (The jello will melt in an outdoor reception, but that's another thread!)

You do not need a firmer cake for stacking. You need a good support system.

I use nothing but cake mixes and have for 30 years. They work fine.

I know people who use straight cake mix with successful and beautiful results.