How does Half Reverse, Half Forward 1031 Exchange Work?!

[Jonn Vidal]

Sale of current 2-unit building taking long to close as we're waiting for Holdover tenants to finally move, despite all expenses paid (moving, new deposit, 1st mo rent).

In mean while, we already bought 1st half of replacement, in Sep 2021.

How do we use that purchase toward first half of the replacement property when original invest property finally sells? 

At what point do we have to make the 1031 official, closing? The listing agent already disclosed its for sale as part of exchange, but I don't know what the next step is as haven't found the other half of replacement property to purchase yet, for this 'exchange'! And what is the deadline to close on 2nd half otherwise nothing counts?

Where is that intermediary guy (from FL?) is he still active on BP? Tsk tsk what to do next to get a 1031 officially started??