Official process would be to call MR and have them issue the certificate for the stay in your child's name. With that disclaimer, if this is for a domestic stay in the US you can edit the name on the reservation to be your child and it should be fine. General FT wisdom is Europe, Asia, etc. are more particular about the names on reservations, so I would definitely call MR if booking a stay there for your child. YMMV....

--Jon