If the gain is great enough consider a reverse exchange - a 1031 exchange where you are able to control your new property first through the use of an exchange accommodating title holder set up by your qualified intermediary.  

If you are trying to buy the asset (you apparently are trying to be an intermediary and arbitrage the pricing difference) then you need a seller who can pass marketable title.You need to know the laws in your state for determining the procedure for sale of real property owned by Decedent's estate.

Go ahead and sell the two but use a qualified intermediary to process 1031s on them and use the proceeds as part down payment on the new complex. 

Hi Brandon, I've administered in excess of 125,000 1031 Exchanges during my 31 years in the 1031 Exchange Qualified Intermediary industry. 

Maybe as an intermediary you could shed some light on that?

There are intermediaries you can go through who have already sorted out all the legal stuff, including here on BP.

Another reason you can't - because you did not setup a 1031 exchange with a qualified intermediary prior to closing on the sale. 

@Jonathan McGarrity there are a few intermediaries out there that can help you and finding one local might be useful.

This way your seller is contractually obligated to follow through and the money is not sent to remove the liens until they hold up their end of the bargain and they have assurance that you will follow through because the money is with a qualified intermediary.

My turnkey middleman (which is what RTR serves as, an intermediary and not the actual rehabber) even intervened and they have ghosted him.