the cost to upgrade the lines to accomodate the tankless system in addition to the cost of acquiring and installing may put you over the top.

That is true too, but actually I was speaking of an extra bedroom in that storage building on the property that someone is now renting to accomodate a child of current renter.Child would still have access to main house for meals, showers, ect with the feeling of their own "apt".

The accomodator sets up an independent LLC to hold the properties until the final exchange is made.

You can replace appliances and redo kitchens and baths with the tenant living in the apartment making certain accomodations if necessary.  

I know we've been having a number of quirks, as we are changing some stuff to accomodate the upcoming (and highly anticipated!)

IMO Homes or lots that can accomodate two should have that option.  

They want their tenant friend to stay an extra 3 months, got burnt by an inspection before, need a flexible closing date to find a new place - accomodating these things are often worth more than money!  

A reasonable accomodation is required, but Landlords are not required to accept applicants just BECAUSE they have a service animal/ ESA.

You do not need to pay for the reasonable accomodation, you simply need to allow for it.

I re-iterated few times that I absolutely need the house empty asap, but given the social issues with virus, I decided to accomodate.