If this looks complicated, it isn't really. Everyone is walking with at least one step-something. Also, Wayne is married to Claudia's sister. That should be all you need to know to make sense of the chart:
Son of Richard, stepson of Claudia, stepbrother of Marty
Stepdaughter of Wayne, cousin of Marty
Wife of Richard, mother of Marty, stepmother of Adam, aunt of Alexis
Son of Claudia, stepson of Richard, cousin of Alexis
Husband of Claudia, father of Adam, stepfather of Marty, brother-in-law of Wayne
Stepfather of Alexis, brother-in-law of Richard and Claudia.