Alright so my sister is getting married. She is quite a few years older than me and I would like to play an acoustic guitar song for her at her wedding. Preferably something that is a "sister song". Any ideas?

I’m looking for as many suggestions as possible for songs for the following:

Acoustic guitar while the wedding guests are being seated

While the bridesmaids are walking down the isle

While I, the bride, enter and walk down the isle

A few different songs for friends to sing. Mostly solo, maybe a duet.

A song for when we walk down the isle as Mr and Mrs.

And the fun part….a good song or set of songs to do a surprise choreographed wedding party dance at the reception.