Really nice to be remembered but I would be careful. The parents may like you but your playing to a crowd who doesn't know you and may have very different expectations. One guy with an arranger keyboard is far from the wedding "norm" these days. If its an older group or very small intimate setting the keyboard will work OK for the cocktail hour, dinner, and maybe early on but its rare to even see a band these days at a wedding, unless its a very high dollar affair with something like an 8 piece show band. And guarenteed they will DJ a lot of current stuff or play along with MP3's as the party builds. Forget Celebration and even the Electric Slide, both way over with. "Party Rock Anthem " Cupid Shuffle" and other more current tunes are whats expected at most weddings. Sorry but the DJ's and especially those with Video setups have taken over that market.
I think the best bet is as suggested above. Do your part at the Cocktail hr. Ceremony if needed, and dinner and have them get a DJ for the rest. You'll be more comfortable and have less worries.

Good Luck

Bill in NJ