With the exception of my chocolate cake, carrot, and Italian Cream, most all my cakes are doctored mixes. I use Betty Crocker for French Vanilla, Strawberry and Lemon and only add Cream Bouquet (an emulsion). They hold up fine. The bakery I used to work for used the Betty Crocker French vanilla recipe as their go-to wedding cake. Just about everyone ordered it! I recently did an Uncle Sam hat with alternating strawberry and french vanilla layers. They were 2 cakes 3-layer's each stacked on top of each other. No problems. And that cake sat out in a humid, warm house for 4 hours. Also did a 3 tier french vanilla Bridal Shower cake and a teapot cake. All good. (they're in my photos if you want to see).