Use ‘&’ if next person to be added (ie Person B) is married to the previous person (ie Person A) – thus looks like A & B
Use ‘,’ if next person to be added (ie Person B) is not married to the previous person (ie Person A) – thus looks like A, B
Thus for a family situation with Father (Person A), Mother (Person B) and Son (Person C) – thus looks like A & B, C