Two or more characters related in some familial way spending time together. No couple posts unless there's a family member involved (usually a child). Do not add pictures if it's just an everyone-type of image with no emphasis on family (post #479353) or if the characters in question are just posing without even acknowledging the others' existence (post #692168). The last rule will be strictly applied to siblings posts due to the sheer number of them. As a general rule, you should be able to fill in the blank of "X and X are doing _____" with something other than "posing for a camera".
Family does not need to be blood-related, but it must be made clear canonically that they are family. Exceptions to this will be handled on a case by case basis.
None of that type of bonding, please. Let's keep the quality up and the incest to an absolute minimum.
For the reverse of this pool, where family members do not get along, look here, pool #3404.