Yup - had the same issue with my dad. See, his girlfriend's granddaughter apparently has the sun shining out of her butt and she is the Example Everyone With Kids Must Follow, according to Dad.
He was horrified that I didn't have DD enrolled in basketball or softball, because the Example was enrolled in those activities, plus more - and didn't I know DD needed to do these activities to live her life well, and she was going to have a weight problem if she didn't do exactly what the Example was doing, and on and on and onandon every time we had a phone call. I got tired of it and told him that a) DD isn't interested in that sport; b) I'm not pushing her into something she is not interested in; and c) the subject was closed as he had his chance to raise his child (me) and I would be raising my child as I saw fit.
You probably don't want to be as blunt as I was with him, but with my dad, only bluntness works. But yes, do what everyone says - I POD all posters who say that you need to stop bean dipping and just tell him - DD isn't interested, but thank you for the offer. If he persists, you may have to have a "this subject is closed" conversation with him. Else he will continue to badger you about it.