Thank you everyone for such great info, I really appreciate it!!

Yes I agree that it is not always diarrhea (a few times a week it is, right out of the diaper, watery and multiple times a day, but the rest of the week it is just really loose stools). I'm glad to hear that it is somewhat normal - both my daughters had formed poops by about 8 or 9 months - even though they were still breast fed, so it just didn't seem right. But he is definitely happy otherwise. I'd still like the mom to go through with the testing just in case because both of my daughters have had a few bouts of really loose stools in the month that the little boy has been here - and that is very rare for both of them (ages 6 and 14 months).

I think a lot of my frustration was regarding the assumption that it was MY job to collect the stool sample and the lack of consideration on the part of the mom for letting it go on this long - but maybe that is my own fault for not being tough about it. I am ok with changing the diapers as long as everything is ruled out, for my family's sake.

Again, thank you everyone for such quick and detailed responses