Is there a taxi/car service company in Boston which can provide a child car seat, if we request one in advance? We realize that the T is usually very convenient and that's what we'll mostly be using, but there are a couple of times when a cab will be useful and we won't have a car seat along.
Fortunately, the family-friendly website FamilesGoTravel.com has this:
And their company for Boston:
Hope that helps!