You are welcome.
The problem if you try to settle is that you will restart the statute of limitation. But you cannot settle without speaking with them so you are caught between a rock and a hard place. If you have 10-30% of what is owed, then I would consider settling now, but you do run the risk of not settling and the statute of limitation clock restarting.
My 2 cents
One could always throw in legal language and refer to it as the 'alleged' debt.
My mistake on settlement was not requiring their signature on the lien release as condition. (Well I did, but they ignored it.) Remember that. Consider a pre-settlement letter for them affirming they will release lien upon payment. If you settle in exchange for a lien release... by all means PREPARE the lien release for them and include it with your settlement offer. ( One can find samples and wording from the records of others, surf mortgage with lien releases in your local County Land Records. Have an attorney review for small fee if you need to feel better.)
If this is local legal person for the bank (debt collector), I would even go so far as delivering the settlement check and picking up the signed lien release simultaneously.
(I'm just another homeowner, not attorney)