The usual number is 6 (5 plus the person with the disability).
CMs issuing the GAC are able to make reasonable changes to that though. You won't have a problem since it would not be reasonable to leave one 10 month old alone. If you had a party of 12 adults, that would be a different story, but being over by one because of a child should cause no problems getting a card issued for 7.
Just so you are aware, there may be situations on individual attractions where there is a limit on the number of people who can stay together. For example, the waiting area will be to small or the seating is set up for one person with special needs plus a companion. There will always be room for at least one person to be with the person with a disabilty. I am thinking specifically about show/theater seating where there may be one disability seat with a single companion seat next to it. Seating for the rest of your party will be close by, but not right next.