@Erasmo Alvarenga, The qualified intermediary who is required by law is the most important member of your 1031 team. 

Your Qualified Intermediary should be able to walk you through your closing/settlement statement and identify those items that are permissible vs. non-permissible so that you can decide if you want to contribute out-of-pocket funds into the closing to offset the taxable boot. 

For all things 1031, it pays to consult with a Qualified Intermediary.

At some stage in 2021 (depending on my tenants) I will be looking to do a 1031 exchange into a property portfolio.I will need a 1031 Qualified Intermediary and a Portfolio Lender to finance the deal.

You would technically not need a qualified intermediary. 

Does intermediary hold the money until it is paid off and deed exchanged or does intermediary pay the identified property with each installment? 

TENANT IN COMMONQUALIFIED INTERMEDIARIES such as @Dave Foster

My 1031 intermediary simply told me to talk to an attorney. 

The reverse exchange just means that you buy the asset first (with or without debt) and the intermediary holds it until you bring in your cash.

I hope your father-in-law already engaged a QI - qualified intermediary for the exchange.