Did you mean to say, "My *sibling* [singular, the decedent] left me as beneficiary to her TRS retirement?"
I don't see how you can "forfeit" this inheritance without disclaiming, but it's a matter of state law. Qualified disclaimers can be tricky, so you need to consult with an estate attorney. You would also need to be sure that the retirement plan will recognize a qualified disclaimer. A qualified disclaimer results in you being treated as having predeceased the deceased retirement account participant. You cannot direct where your share goes when you disclaim. Where the share that you disclaim will go will be determined by the beneficiary agreement and the terms of the retirement plan. That could end up being the decedent's estate if there were no other primary or contingent designated beneficiaries, and that might not produce the desired result. You might be better off just receiving the inheritance and gifting money to the kids. But an estate attorney can help you with this.
