14 in-laws grazing and watching TV? I'd go on a retreat and let them enjoy themselves!
Seriously, though, sewing/quilting will be seen as removing yourself from the group festivities. Even if it's handwork. Personally, I'd think it rude. Not knowing your situtation...like, how often do you see these folks, did you offer to have the doings at your home, or was it foisted on you...well, it's hard to say what to do. Think of it this way: is the time spent sewing worth the feelings that will be directed at you from your actions or do you care? Personally, I'd be part of the group, knowing it only happens a few times a year.