@Thomas S. so we can give advice and we won’t be in any legal issues? 

Or would their be legal repercussions if they do background checks and they find out that they don't want to rent to these people?

That means that he is legally required to work in the seller's best interest, which usually means getting the highest possible price, at the best possible terms and closing on the timeline most beneficial to the seller.As others have pointed out, getting a buyer's agent is at no cost to you. 

Are there any creative but legal ways to use my personal funds and the SDIRA on the same projects?

heres a thread with some info on RUBSYou can do it yourself or hire a third party for a small feehttps://www.biggerpockets.com/forums/432/topics/94656-rubs-for-apartment-building

If I were you, I would contact an estate lawyer, or have the siblings contact one, to legally see what the other 4 siblings options are.

I know its not legal.. but I self insure myself in that regard. some say its recession proof and some say not.. my banker says not.. he says when economy gets tough they just won't spend 200 bucks a month to store their stuff they either up and leave it or move it somewhere else.. so that's two opinions.my units were quite unique one they were A class and two right across the street from 300 floating homes and all my tenants save a very few had house boats.. so I kind of had a captive audicance and once I got it converted to mainly all houses boats..

@Matt SearsGo to the tax & legal forum - you can meet a number of experts there, as well as ask your questions.

What legal steps do I have to take to form a partnership in terms of financing.

Alexander, Yes a great RE lawyer is over PDX legal solutions, tell Henry Rau that I sent you his way.