Hmmm, I know how frustrating this can be bc I used to feed kibble, then moved to homecooking, then raw - and it was the homecooking phase that was so frustrating (partly bc this was also when Marcel had giardia). Anyway, first - what is your long-term goal with what you want to feed - bc it sounds like you're still on the fence, which I totally understand (I would be too).
The problem (besides possible allergies) might be that you're upsetting the cal/phos ratio. Are you feeding more than 15-20% real food (of the total diet)? If so, the ratio is then thrown off. You can still add real food, but I wouldn't add more than 15-20% of the total diet, that way - you won't have to supplement. I'd probably do an elimination diet - adding one real food back in at a time.
The other option to consider is feeding raw in the evening. It would be a great nutrition boost for them and no supplements are necessary. You could do Natures Variety pre-made or Primal or whatever. Just a thought, if you don't want to do straight kibble. Or, what about mixing in some premium canned? That's healthier than kibble and is balanced. Lots of options.
