Billy Kaplan's family

Jeff Kaplan: Biological father


Rebecca Kaplan: Biological mother


Tommy Shepard/Speed: Twin brother (see Scarlet Witch)

(and two younger brothers)


Wanda Maximoff/Scarlet Witch: Mother (altered reality and reincarnated Billy and his brother after their souls were stolen)


Pietro Maximoff/Quicksilver: Uncle (Twin of Wanda)


Lorna Dane/Polaris: Aunt (sister of Wanda & Pietro)


Erik Lehnsherr/Magneto (deceased): Grandfather (Father of Wanda, Pietro & Lorna)


Shapeshifted:
Teddy Altman/Hulkling: Ex-Teammate/Fiance (?) (Hasn't seen him for a while, isn't sure where they stand)


Alternate timeline Erik/Magneto: (technically) Grandfather (After the older Magneto's death, Wanda accidentally altered reality when she was upset and wished for her father to be back. She ended up pulling this Magneto from his own timeline.