Homer and Marge are Bart's...
Parents
Selma is Lisa's...
Aunt
Bart, Lisa and Maggie are Herb's...
Niblings
Ling is Patty's...
Niece
Maggie is Homer's...
Daughter
Lisa is Maggie's...
Sister
Marge is Homer's...
Wife
Bart is Maggie and Lisa's...
Brother
Bart, Lisa and Maggie are...
Siblings
Bart is Homer's...
Son
Bart, Lisa and Maggie are Homer and Marge's...
Children/Kids
Herb is Bart's...
Uncle
Abe is Bart's...
Grandfather/Grandpa
Abe and Mona are Lisa's...
Grandparents
Bart, Lisa and Maggie are Ling's
Cousins
Mona is Bart and Lisa's...
Grandmother/Grandma
Bart is Herb's...
Nephew
Bart, Lisa and Maggie are Clancy and Jacqueline's...
Grandchildren
Homer is Marge's...
Husband
Lisa is Abraham and Mona's...
Granddaughter
Bart is Clancy and Jacqueline's...
Grandson