We. The Revolution

When I got this, relations with all 4 members were above 75%. More testing on thresholds is probably needed, but I would at least shoot for above 50% on everybody. If you can, spam giving to the orphanage as it's the one family action that raises relations with everybody. Also, the few occasions that family members have an opinion on the trial is also an across the board increase or decrease, no split opinions. On the opposite end, helping to build the monument, prepare for the case, or choosing any action which results in not spending time with family (such as going to the gambling den) automatically decreases relations across the board. There are some scripted events which force you to not spend time with family too. For all the other family actions, it's mostly a shot in the dark to how severely they affect each member, but in general I found that the majority will have their opinions less severely affected and the minority will have their opinion significantly affected. There are some actions which one or more members have no opinion on too. My main strategy was to build up 3 members as much as possible, and once there's a good buffer on them, repivot to the last one I was neglecting.