I'm doing my best to bite my tongue as we've all repeated ourselves over and over again. However, I do have one thing to add.

Lily & Roxy can easily eat the same adult dog food. Before I started buying my own dogs' food (and now I barely buy anything for myself -gasp-), we fed Nutro Natural Choice Lamb & Rice Small Bites. The small bites are actually better as they reduce the chances of bloat.

I am curious as to why you think they need to be fed different formulas and where you go this information from?