There are several options open to people if their spouse does not return the Acknowledgment of Service to the Court, but this depends on the fact relied upon in the divorce petition.
For example, if you have used unreasonable behaviour, 5-year separation or desertion, you can proceed without the return of the Acknowledgment of Service, provided you can evidence that they have been served with the papers.
However, if your petition is based on 2-year separation or adultery, you will require your spouses’ express consent/admission and the return of the Acknowledgment of Service.
If this is not achievable, you can amend your petition and rely on a fact that does not require your spouse’s consent as mentioned above.