-Asking the potential lender to collateralize the difference on the borrowers SFHs. 

The bank would see that my home is work $300k so gives me a $300k loan and uses my home as collateral.

Hypothetical question; asking for a friend.What are the prospects of purchasing, say, a triplex using the equity from another duplex as collateral? 

But I will say that I don't think the next downturn will be focused on the RE industry, but we'll likely have some collateral damage to deal with.  

Can the property still act as collateral to the non-recourse 401k loan if the hard money lender holds a first lien position? 

Could you use it as collateral?

If you (the buyer) fail to pay, then they have their original property as collateral.

The BK court won't let him use the house for collateral, nor does he have any other assets to pledge as security.He's willing to be generous with a fee

Raises the real estate you’re dealing with to put as collateral, you can also bring in other properties you may have with good equity to strengthen that security for the private money partner

Some may allow you to have an equity line of credit (LOC) with that as your collateral.