Would we be able to collateralize that house (as a form of guarantee) to help on the financing of the new one? 

Beyond just the borrower characteristics, you might want to remember the broader 5 'C's' of Credit: Character, Capacity, Collateral, Capital, and Conditions.As a smaller lender myself, I focus on the Borrower first and their ability to get a project across the line with as little headaches (to me) as possible. 

By purchasing property within the IRA, you can use non-recourse loans-where the property itself is the only collateral-to finance a portion of the investment.

The right question is what is the collateral backing your note.

Cross-Collateralization: If you have other properties with equity, you might be able to use those as collateral to secure better loan terms or additional funding.4. 

Usually the best way to get around this is to cross collateralize another property you own.

"Additional Insured" on Insurance Policy to Property as CollateralHow specifically should a private lender be mentioned on the owner's insurance policy to a property used as collateral to a loan.

It indicates that the property was used as collateral for a loan.

@Edward Heavrin: Both options, but at a high enough equity you kind find long term mortgage products that will allow cross collateralization, so you can use those high equity or free and clear assets in lieu of down payment. 

Since your home is collateral on the loan, you could risk foreclosure if you're unable to pay your new loan amount.