We also have occupants sign an agreement saying they are giving up possession and all rights to the property in exchange for the cash for keys.

It can be done under agreements that can vary from having the first tenant being held responsible, as in the case of simply sub-letting, or the owner could agree to only hold the tenant in possession,which is not so likely.

This prevents a default on the loans to make sure you maintain possession.

A foreclosure, judicial or non judicial, doesn't restore possession in CA.

You may take physical custody of the original note as endorsed and you may give that to the servicer for custody or retain possession and put that in a safe, like a safe deposit box.Then you receive the request to accept the deed from the borrower and the quit claim deed can be made.

If you can convince the HOA to file for this and the judge agrees, the court will order a separate third party to take possession of the property.

The process of moving the property from the ownership of the owner to the state's possession (not necessarily 'ownership') is called Escheatment.

The security deposit is deposited into our security deposit trust account and remains there in its entirety until a future point in time when we regain possession of our unit. 

But one day of post-closing possession... and your 75-120.3(d) "shield" is out the window.

When the Mortgagee takes possession of the deed, they are now the formal owner and they can rent the property or sell the property or do what ever they deem fit.