Am I responsible for a lein on my house 1 year after completing the deed in leiu on my house?

It would be tricky to give a definite answer to this question without more details. However, if there was no lien on the property when you completed the deed in lieu, I wouldn't expect any future child support debt to attach to that property - that property has nothing to do with you anymore. If, as you've said, you've previously provided evidence to the bank that there is no further liability, this seems to be more their problem than yours. As long as you are otherwise current on your debts and the property is no longer associated with your name, it seems very unlikely that there would be consequences to your credit or future credit worthiness. You might consider consulting with a local attorney, or try submitting a consumer complaint to the Consumer Financial Protection Bureau at www.consumerfinance.gov to see if that will stop the continuing communications from BoA.