Your personal financial situation (tax records/bank statements and personal financial net worth statement)3.

@Jeremy Hartwig, I know this is a slightly glib answer, but property is worth what a willing buyer and willing seller can agree on.You can use cap rates, but admittedly those can be useless too, for similar reasons that Kevin outlined.  

Money today is worth MORE than money in the future.

It may not be worth it if your long term rent and cash flow are adequate.

I am not an attorney but I have studied this a bit so take it all for what it is worth.

It's possible, but seems worth the risk. 

He has bought and sold over 300 million dollars worth of real este and doesn’t care that he’s going to lose some money by almost giving me this property.

The reason I want to do this is so that the ADU is worth more on an appraisal.

While they do eat into rental margins the larger profit came from the sale and the added rental profit was not worth the hassle of being a landlord.

These can be fairly automated for you as well to help save you 10% which on 2 units could be well worth it.