What is your affiliation with them and why are you so anxious to defend them?

It's amazing how quickly people back down when they realize you're prepared to defend yourself.

Read this book: https://store.nolo.com/product...The author is a lawyer who used to defend tenants. 

Common sense will tell you something even if you don't see the details of the case but notice that the defendants are previous landlords.

It would be foolish for you to represent yourself in a lawsuit so find the money to defend.

If not, and the parties (plaintiff and defendant) hopefully reach an agreement that is presented to the judge.

Depending on the language in your lease you should be able to make a good argument to defend your actions. 

“Seller, as a condition subsequent to closing, shall remove and sever the subject properties from the condominium regime.”The agreement was to sever post-settlement so I assume you'll find the title policy insures as part of the condo and subject to the declaration etc. and as @Peter Walther suggested, the title claim would be denied on that basis.Without seeing the original agreement nobody can give a reliable answer but based upon the info provided that would seem to leave as defendants (1) the seller and (2) your real estate agent or attorney (if any)... the latter for not researching this and/or leaving severance open as a matter that could actually be handled post-settlement.Regarding who you sue first... the answer is everybody, or you may lose the right to sue someone you should have later.

The defendant, our tenant, did show up for court and was called up to the bench next to our attorney.

Even if they lose, you spend a lot of time and money defending yourself.