I haven't noticed anything with DS' poo before. I got him to use the toilet for poo as soon as I could, though - told him that he was doing 'big kid poo' and I didn't want to have to deal with it anymore, that's what the toilet was for. Bit 'arsh, but it was true!
DS ramped up his feeds in NZ when things got a bit tense in the family, but didn't notice a difference in his poo (I usually do a quick reccy in the bowl, just to gauge where he's at). Maybe it's something else she's eating? Dairy?