We have an interim construction loan in process and the customer is requiring additional funds to complete construction. a right of recission was done initially since part of the loan was refinanced from another institution. Would the advancement of these new funds be rescindable?

What is the collateral? If you have their current residence, then yes. If only the new home secures this loan, RofR is not required (nor was it before).

The collateral is currently 12.5 acres and are living on the property in a cabin. ROR was done intially since they are currently living on the property as their homestead. So a ROR will be required for the advancement of new funds with just an additional work contract. Will any other documents be required for this advancement of funds?

If you do a modification, only a RofR and Flood determination is required (although you can most likely rely upon the previous SFHDF).

If you do a new note, all new disclosures are required.