well, I think the policy is they can not hold infants.
But, I have the greatest shot of mickey, and my 9 week old, with my almost 2 and almost 3 year old as well. Yes, Mickey was holding the baby. And, truthfully we had a couple characters take the baby, and for a long time. Mary Poppins (when she was in the toystore, and no one else was there but us), held the baby for almost 15 minutes while we did the kidcot station there with the two other kids.
So, I would go with the expectations that characters can't hold the baby, but it might happen.
I do know (and not sure if it will apply since your child is 9 months, we got yelled at when mine was 15 months, not sure it makes a difference), that photopass will not take a picture unless a child has something on their feet. My 15 month old kept chucking her shoes, we lost one and had nothing (she was held most of the time, or in the stroller, and we had socks with her) for her to put on her feet. The photopass would not take her picture without something on her feet. Thankfully her robeez, which she could not take off were back in the room for the rest of the trip.