How To Write A Child Support Debt Forgiveness Letter . Agreement for child support sample letter. A child support arrears forgiveness letter is a document that can be used by a custodian parent (or legal guardian) when they want to waive the responsibility of the other parent (or legal guardian) to pay child support. Sample Debt Letter Download Printable PDF Templateroller from www.templateroller.com Start writing your goodwill letters now. Joe and jane brown, whose father is jack brown, are my two children. I’m writing to seek that the child support ordered in case #123456789 be increased.