I'm interested in BRRRR's with single and multi family.

There are DSCR loan options where you can cash out up to 80% if you and the property meet certain criteria: if you have a middle mortgage FICO score of 740 and above you can do a 80% cash out refinance if 1-4 units (so single family rental or 2-4 units).

Investment Info:Small multi-family (2-4 units) other investment.

There is another option to look at assumable loans here in AZ and see if you can get into a lower interest rate. 

Totally a viable option but keep in mind the documentation of the process and making sure that YOUR material participation does not exceed anyone else in the home - for example, your cleaners or maintenance people. 

I've heard of "blanket mortgages" which I thought might be a better option for me so I could use the equity in both properties and only need to get one mortgage.

Either of those would be much better option then a blanket loan to (as mentioned above) the issue with partial release. 

Our big goal is to have a large 8/9 figure+ portfolio by our mid 40s, owning multi-family, retail, and some single-family homes.

They say they will sign my lease and also sent me an addendum to sign allowing them to sublet.There are a few reasons why i like this option for this property, but im wondering how to background check the company and the individual they are assigning to ensure ill be paid monthly as they claim. 

I have a multi million dollar development project on hold because of it.