I have had a couple of addresses over the years and usually I have used UPS, but lately I have seen a lot of virtual option popping up ... earthmail ... regus ... digital mailroom ... there seem to be quite a few.Would anyone have feedback on the best route to go?  

DSCR loans could be a good option if you want to continue to grow your rental portfolio.

I definitely prefer this option as the whole point is to get built-in equity.

She is absolutely crushing multi and ADU multi in all parts of LA and knows the regulations for all of these options

My team on the ground there handles everything from sourcing deals to renovation, and we've worked with hundreds of investors each year to make these properties cash flow.We’ve built up some solid relationships in Detroit—whether it’s general contractors, agents, or property managers who understand the ins and outs of Section 8.

Definitely look into HELOC/cash out options, but if those don't work in terms of rates or availability I'd suggest using the existing cashflow from your multi to offset a primary mortgage, and then find a primary with an ADU.

Do you have a source? 

By sourcing directly from trusted factory partners, Griffin Modern saved significantly on key elements like the Pivot door, floating staircase, glass handrail, and casement windows—items that normally cost 30% more when purchased at retail.

If you were not purchasing with hard money, and had the option of putting it in an LLC, I would. 

Then search the internet and read 50 articles about syndication from various sources.