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If the CC isn't reporting monthly now, then doing anything, other than having it deleted, would drop her scores some. The CCC will report a new DOLA with the first payment. FICO often interprets that s a recent baddie, if it says "charged-off" anywhere within the acct.
Her best bet is to either offer a PFD for a one-time payment (you could press using their settlement offer) or a modified-PFD asking them to remove any lates and/or charge-off reference again making a one-time payment. She'd really want to avoid making payments over time. The CC would reneg and send it off to collections. Making regular payments would drop her score. Also, making a payment could reset her SOL, placing her in a position to be sued. If paying in one lump isn't an option, then there's not too many options, I suppose. Just make sure she gets the agreement in writing. Also make sure it is the CC offering this rather than a collection agency. To confirm, tell her to pull her CRs and make sure that the CC is reporting a balance.