So you wanna crush your family? Sounds like fun to me
You hadn't mentioned the frequency of raises preflop, so I'm assuming it's low, and besides everyone calls the raise anyway so you'll have great odds
You want to play hands that have the potential to turn into monsters. Suited connectors, small pocket pairs, suited aces, and probably suited kings as well, make up most of this field. These hands will thrive off the massive implied odds they get postflop when you make a strong hand or strong draw.
The other aspect to keep in mind is your pot equity preflop. You want to make sure you're raising hands like AK/AQ/AJ/ATs, knowing full well everyone is going to call. If you have 5 players with you going to the flop, then you only need 17% pot equity to make every dollar going in preflop +EV for you.
Build up big pots with those big pair hands, and just fire at them straight through the river when you hit. The variance in this type of game is large, but the returns are equally monstrous, for when you do win the pot, it's quite large.
Have fun owning your family.