Heirs and Beneficiaries: Unable to Establish Contact with a Beneficiary

My question involves estate proceedings in the state of: Arizona

Executing a Will

Background:
My wife and I are executors of a will. The will specifies, among other things, that monies be divided among several organizations.

Such that one gets 25%, another gets 15%, and so on.

The beneficiaries are all non-profit organizations, e.g., a University foundation.

One of the beneficiaries has proven difficult to contact. So difficult that after several months of intermittent attempts to establish a dialogue neither ourselves or the lawyer handling the estate have been able to establish sufficient contact to determine how to get the documents and monies to the organization.

We are at the point in the estate that the beneficiaries need to sign off to get the checks. We are at the point of final distributions and closing the estate. We cannot proceed, however, until all the beneficiaries are accounted for and sigh off.

Question:
In such a case where it has not been possible to establish meaningful/consistent contact or communication what does one do?

Can we change the beneficiary to an organization similar to the one specified in the will? And in keeping with the deceased's general guidelines?

Or divide the monies designated among the other beneficiaries?

What is the procedure?

Thank you ,

Earl

Heirs and Beneficiaries: Unable to Establish Contact with a Beneficiary