Actually, the family tree is a fun extra but you can totally follow the show without it. The real trick is to just let the first few episodes wash over you and the names will start to stick. Trying to memorize everyone right away makes it feel like homework. The show does a good job of making the main characters clear pretty fast.
Drew a friend into watching it and she showed up to brunch the next day with three pages of notes and a conspiracy board. She actually tagged @stellarivera in a rant because she said the show needed a whole class period to explain the timeline. Her notes had little arrows going everywhere with question marks next to names like "Old Claudia?" Took her like two watches before she stopped yelling at the screen.