Legal Question in Family Law in Connecticut

I'm not sure what you mean by "nullify an existing QDRO." If the document was executed by the parties and the court signed off on it then it presumably means that the administrator of the retirement plan approved it.

If you both have decided that you want to distribute the retirement plan differently now, you would need to do a new QDRO because the administrator of the retirement plan can not distribute the monies other than by way of QDRO.

You will need to get a court order and then there is an issue of whether the court has jurisdiction at this point because property settlements are not modifiable after the divorce.