I think it will be about 3 things, 1 Trust, 2 Reliability 3 Usefulness, you will have to measure people on a scale of these 3 things vs. Negative traits. Im not talking about family that are elderly or children, those are your wards. I will prioritize each person in that order. If I cant trust someone it does not matter what they bring to the table. If I trust you and your reliable under moderate presure, but have nothing, not even a useful skill, I will take you and teach you and make good use of you. I have 2 friends that I have known for 30 years, one has all 3, the other has the first 2, I would take both over a few relatives that are wealthy and a couple have useful skill sets, but I would not accept them into my SHTF community because I dont trust them.