I suppose the term may be slang for the sake of conversation where they are saying, you can put your contract with them and they will wait for the third party (end buyer) to be produced before preparing documents but I would not personally refer to that as an "Open" deed, since the only party to be added would be the party who steps in as Buyer or Asignee.

Do not ask advice from the turnkey salesmen, they are not a disinterested 3rd party.  

Then when we were granted eviction all parties would be removed from the unit and we changed locks on all doors right away and secured.

This allows me to close sooner than the date listed if all parties are in agreement.

I'm looking at a property from a third party.

The hard part is done, finding the deal. 

Both parties must sign for the property to be sold, and if you do take a Gurus advice, I suggest the seller to don't spend the money just in case if someone came calling they might call that mortgage fraud.Joe Gore

If you are doing it through a private sale then you definitely need to have a 3rd party do some research and provide you info. 

Managing expectation of all parties to the deal and being transparent builds relationships (Family or not).

One month before the scheduled end of the lease between these parties onthe said property (including any extensions as provided in writing by the Owner) andprovided the lease between the parties for the same property is not and has not been indefault, an Option to Purchase Agreement for the subject property will be granted inwriting and delivered to the lessees.