I know that a "subject-to" (sub-to) arrangement might work, but is there a way to release the other spouse from liability when using sub-to, or is refinancing necessary?

What @John Underwood said ^^^ there is no way to easily control the temps.And the way my brain works as a lifelong business man is....it sounds like possible HUGE liability issue.

A Heloc is looked at as a liability and the underwriter "Must" use the Maximum payment even if you have not used the Max Heloc amount.....

A new loan will not take your other loan as "equity" because it is not, it's a Liability. 

They were so worried about liability of the people coming over that they were talking about kicking the tenant out because they didn't get their approval for it.

The last note was that i learned what a series liability is and was curious if i may be better off doing one of those because i have 2 properties and plan to slowly add more (Maryland does not offer series llc but wyoming does).

Many states have laws against it and you run the liability and risk of pissing buyers and sellers off as the middle man.

That's just a rule of thumb for a quick calculation.Flipping is could be cost intensive and then bring tax liability when done as a one off, for instance if you did 1 per year maybe it's not worth it. 

Everything in the home will get double usage, especially the appliances.....Also make sure your liability insurance knows that they are now responsible for insuring 6 people.This just sounds like a bad idea to me....

(e) When any debtor or mortgagor conveys his interest in property subject to a mortgage prior to sale wherein they are released from liability for the debt, his right of redemption under this article is terminated.