Can a life estate deed in my children's names (of legal age) be filed before a lis pendens by the servicer (NOT the owner, who is unknown; validation requested and never rec'd) on my property and protect it for them against foreclosure? The mortgage has been in dispute for 6 months (State: NM). Thank you.

Please clarify in steps who owns what and where, and what is happening with each.
I assume that you want to give the house to them with you having the life time use? Otherwise you face the same debts as you do now. You may have to pay a gift tax. Talk to a lawyer. Maybe you can 'sell' them the house at fair market with the minimum IRS allowed interest on a loan.

If there is pending litigation and you are trying to use this as an end around to get past the litigation, it won't work and you could be charged with fraud.

A lis pendens is to protect potential bona fide purchasers to whom you might sell the property after the lis pendens has been filed. It's not necessary in the case of adult children of the seller, who presumably are not BFPs anyway. Not necessary because the transfer of a life estate would not be valid against the prior mortgagee, or against a purchaser at a mortgage sale.