When it comes to major CapEx expenditures (roofs, retaining walls, windows, plumbing) we prefer to undertake them on our timeline rather than Murphy's.  

The lot itself is also much more steep than I anticipated and would require considerably more grading and retaining wall than we care to take on. 

Can we retain a professional that would handle all of this?

In the power of sale scenario the borrower retains possession of the property throughout the sales process (lender does not need to seize the property).  

If you have the most vested that will need to be shown and likely recognized and if you want to retain the property the court may well set a value and have you buy the others out.

You can also say you retain the right to enter, make improvements, retaining the rights to the  industrial fruits of the land and keep personal property.You can limit the rights conveyed on a short term lease, the issue is or could be, getting the sellers out if they go over 30 days, that's a judgment call.  

Deposits were retained do to the termination of the leasing contract. 

I also want to do some work on the place to increase the under market rents, which will show a stronger rent history should we decide to go for a construction loan to add another unit at refi time.Using your scenario, I'm also assuming they would retain ownership of the property, which could put us in the sticky situation of putting money into a property we do not own--something I am not comfortable with.

You hear on occasion about the super star fund managers getting more, but nothing close to the amounts that these note funds retain.  

You retain management and control of the checkbook.