MIL wants a dance with her son... Sure. Grandma? Come on!

We are having a small intimate wedding. 50 people, Sunday evening, 4 hours, etc. My father and I do not have the best relationship therefore I am not 100% if he is coming. My mother is walking me down the aisle but she is not interested in slow dancing with her daughter. FH and I decided previously that we were going to only have our 1st dance and then begin the reception. FMIL comes to me last week very excited, saying she has picked out the song for her and FH to dance to for the mother/son dance. My first thought was a mother/son dance may be a little odd if that was the only one taking place, I’d rather not have that at all. I thought about it long and hard and decided I can deal with 1 dance if it will please her but now FMIL is saying she wants FH to have a dance with Grandma too… Am I being selfish here when I think in my head HECK NO.