A modification does not satisfy and replace an existing loan. The original obligation continues, even if you change other terms or add additional money.
Below is the definition of a refinance. You should also read the accompanying commentary.
1003.2(p) Refinancing means a closed-end mortgage loan or an open-end line of credit in which a new, dwelling-secured debt obligation satisfies and replaces an existing, dwelling-secured debt obligation by the same borrower.
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