Let's keep this as simple as possible....Ex 1: 3 single-family rentals, value $300-400 each.

He sold his to the bank where mine was easily transfered to my ex's families llc.

This is a tough one since you haven't even accounted for all of the expenses - maintenance, cap ex, vacancy, etc.

TLDR: I'm buying out my house from my ex-boyfriend in Seattle (King County), Washington and I'm struggling to find what the REET if I'm buying my ex's stake in the house.

I am suggesting finding areas like this vs. major cities that can ban STRs any moment (Ex: NYC and Dallas).

Whether its your tenants, creditors, attorneys, the boogeyman, crazy ex etc. you're afraid of.... none of the wonky asset protection strategies aid in preventing the liability or claim from arising and add no additional protections, anonymity or preparedness.

but all in all there is little to no appreciation in that area so not really sure why anyone would buy in a market where what ever cash flow you make goes back into cap ex over time like it did for me.

Cash flow should be after best estimate of expenses and maintenance/cap ex will be needed.  

I just had the best tax return year ever. ex.

I will also set aside cap ex, vacancy, maintenance from the cash flow every month.7.