Having a large family myself, I truly understand how hard it is to get a good family photo. Even at $20 for an 8x10 if it's a good picture of your family, don't loose the opportunity -- buy the print
. You will cherish it forever and it will be cherished long after you are gone. Why chance it that you're camera took a better shot only to find out, when it's too late, that you really didn't get a good shot.
If a few good ones come up on the photo board -- buy the photo. Trust me, you'll have lots to pick from and don't hesitate to have the photographer pose you a few times so you have lots to pick from.