Mortgage question

FH, his friends (who are brothers), and i are looking to buy a two family house together. FH and I would move into one of the parts, while the brothers would move into the other. All four of us would be partial owners. Now, what happens when someone wants to move out? Where do we get money to buy them out and is this even possible. We are all first time buyers, and thought it may be a good idea, considering that the four of us can come up with a great down payment and we would have no problem paying the mortgage every month. Is it too complicated?

I'm not asking for free legal advise or anything, I'm just asking for some general info and/or advice... If these questions are overstepping boundaries, let me know and i will delete. None of us have an attorney, but we don't want to go to one and get laughed out of the office if this is something that will never happen

Thanks ladies