Really doesn't matter who you invite to the rehearsal dinner, as long as it's consistent. Like, we only invited wedding party +1, officiant/spouse, and immediate family (including grandparents.) Wanted to do out of town guests as well, but my wife's family had like a million out of town guests, and I had like three. Would have felt pretty shitty a) asking my parents to pay like a billion dollars to host a family reunion for my wife's extended family (the inevitable result of them ever getting together anywhere) or b) only inviting some of my wife's family from out of town and offending everyone that wasn't invited. My relatives from out of town threw a fit until I calmly explained to them the situation, then they apologized for being cunts. Everything worked out great.