Wedding Resources

Does anybody know a lot about wedding photography? I'm getting married and I was kind of blind-sided by this request. First, let me preface this with the fact that I am not having any extended family in town (no aunts, uncles, cousins... nothing) only immediate (Mom, dad, brothers and sisters.) I got this in an e-mail from my photographer: "Thanks for the shot list. I would also like to request a good contact number (ie) cell for a member of your's and Will's family who I can count on to make sure all members of each family are present for specific photos on your wedding day. This person has to be responsible and alert to what shots I will be taking at certain times and have the right family members present to complete the photos. This will relieve alot of pressure on all parties involved and make for a smooth transition. I will also give them my cell number so we can communicate back and forth as needed." This is the first wedding in my family and my family doesn't get to see me very often. I don't want them to have to spend all day rounding up kids for pictures. I want them to be able to enjoy it as the parents of the bride should be able to. Is this a normal request, and is it required? Couldn't we just give him a checklist of family members and he could go down the list like role call?