Yes if you don’t have mortgage history this validates your primary house expense 

I have a group of friends that they are looking to invest in Real Estate in some deals together, but we are not clear on how to make sure we structure the partnership correctly.I am  in real estate investing since 2018 where I invested in Single Family on my own and holding rentals as well, but I have never done a deal with partners.

You definitely aren't going to have a great predictable return, especially in the short term, if you try to invest turnkey; at least at the single family and small multi-family level. 

I have databases consisting of 1,341 lenders for RE as well as close to 20,000 contacts at family offices, hedge funds, endowments and pension funds. 

P.S: All the applicants have good credit scores, 3x income, and no criminal or eviction history.

Investment Info:Single-family residence fix & flip investment in San Antonio.

Generally any multi family purchases 5+ units is considered commercial, and although many lenders offer financing, the down payment requirements will be slightly higher..usually 25-35% depending on the number of doors.  

In Denver, I'm considering buying the property Nextdoor to mine and renting my current (2Bd1Bath) Single family home.

HOWEVER, a lender might look at your past history and not approve your application because they know even if you meet your obligation they are really underwriting an investment property.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?