Fiance keeps adding guests

My fiance keeps adding guests to our wedding. We are 4 months out from our semi-destination wedding. Every so often (since save the dates went out in September) he says "X and Y have to be there, but that's it, no more" until a few weeks later when he thinks of someone new. He invited one of his friends and his wife without asking me or telling me until 2 months after the fact. Now he wants to add one of his cousins who will be a family of four (I want as few kids present as possible) because his aunt scolded him that he invited one of her children but not the other. We have the chairs for them to be seated but I said no based on principle and that his aunt can't determine our guests, he's never mentioned he wanted them to be there until now. He's not that close with this particular cousin and they've never spoken to me at family events. Plus if we give in to his aunt, I worry that she and others from his family will demand we invite more and more people. We've gone from 35 to 45 guests since save the dates went out. Should I tell him he can invite them or DRAW THE LINE?