If all of them are joint and severally liable, and their income and debt ratios otherwise qualify, this would be the equivalent of a stay-at-home spouse with no income. 

But it would only makes sense if we had an equivalent amount invested, right?

The challenge is that you can rent an equivalent house for about $2,500 a month as a long-term rental.

Title agencies require guaranteed, hard cash or wire equivalents. 

If you think you're going to be spending quite a bit sent up a Pro Extra Account at Home Depot and the equivalent account at Lowes. 

  $96K a year...or the equivalent of a $120K annual salaried  job at a 20% tax rate. 

You will pay the equivalent of 12 points just in fees.

Both had rooms they rented out in their own home so it wasn't completely equivalent to my properties, which are not shared, but it confirmed that there was as steady stream of midterm guests in our area.

I'm getting lost on the refinancing part - refinancing at a 25% equity stake...is this equivalent to putting 25% down and getting a loan at 75% LTV?

That's equivalent to about 415 average home size swimming pools.Get copies of all the bills since the person was delinquent and see what is going on.