Our grandson, age 7, sees his dad very little. The result of an affair, his wife refuses to let our son see this child. Our grandson knows he has a half brother and sister that get to see their dad - he thinks this is really unfair and wants to know why he can't see his dad, too. We have a strong relationship with this grandson and a reasonably good relationship with his mom. Obviously, our daughter-in-law's stance on this has strained our relationship with her. Question: how and what should his mom (and us) say about his dad and the lack of contact with him and with his half siblings, who all live within 2 miles?