I always hear people say "I wish I should have made the switch sooner" because it takes a lot of time and effort to get all of your tenants and systems switched over to a new way of doing things.So with that said, pick something NOW. 

You take the $$ hit now and plow forwardYou move it up some and in smaller increments and they stay for at least awhile longer ...... you drop the $$ when they leave and get market..... your $$ outlay is farther down the road....You leave it "as is" and just rehab as the tenants leave.....but you leave $$ on the table for a long time in some cases if the tenant never leave.You need to honestly look at how much the turn over rehab is gonna cost you and how quickly you can recoup that by being at market sooner rather than later

The goal here is for both of us to win and I don't think refinancing is a viable option to pay him back sooner due to ADUs still being fairly new to the market.

I am wondering if it’s wise to refinance the 84,000 for 30 years which would basically double my return and buy another one in a few years or do a cash out refinance for 30 years and use that money to buy property sooner.

As far as delegating responsibilities - the sooner the better.

@Justine ScheuherThe sooner you tell them the better

Sooner you can get that tank out of the ground the better.

When I coach young agents, sooner or later they ask me about working with investors, because it seems like low hanging fruit to them.

If the property is sold, then the IRR increases, and increases faster the sooner the property is sold:FV = PV x (1 + r) ^ n, where FV = future value of investment (total cash flow + net sales proceeds + initial investment), PV = present value (initial investment), r = IRR, and n = holding period (usually years). 

NY attorneys even suggested that the parties try to work things out amongst themselves because the courts don't typically hurry to a decision.Although you are on the outside looking in, presenting an offer/contract to the kids can motivate them to make a decision since they see a deal is already on the table.Hopefully this can all work out sooner than later!