It was not the same law firm-it was a law firm attempting to solicit my business and defend me.
What law firm
"was not the same law firm"? You've mentioned only one law firm; the one that offered to defend you in a potential lawsuit to collect a debt. And according to your posts there is not current lawsuit because of your payment plan with the creditor.
Are you fearful that the firm that solitude your business to defend a potential lawsuit by a creditor would subsequently represent the same creditor in a suit against you? That the creditor might file despite the payment plan?
Let's kill all the birds (real or imagined) with one stone by getting a letter from the creditor noting the payment plan and its agreement to abstain from filing any lawsuit by any law firm provided that you comply with the plan. Then keep accurate records of your payments.
Good luck