The mortgage is paid (w/proof) among 5 family members, even though 2 of us don't reside there (we want our dad to have a place). We divide the mortgage equally among us 5. One of the members is the legal owner (he had the credit). The agreement is that when dad passes the house will be sold & $ will be distributed among us 5. The legal owner has never provided any paperwork to us to assure us that will happen. What legal documents should I have to secure this in California.
If one member of your group can't pay anymore, or just decides not to, then the rest of you will have to cover their amount.
When you do get added as an owner, be aware that there are tax implications if some of you are owners living there and some are not. When you sell, the capital gains are different for those who lived in it as a primary residence, and those who didn't. It may also make a difference on your taxes each year. So read up on that, or ask the real estate attorney when you meet.