Multiple nil rate band use?

I have an estate where W has been married twice. First husband left his estate to W. She then remarried husband 2. W then died leaving her estate in a life interest for husband 2. Unfortunately husband 2 had lost capacity by this stage and could not agree a variation of the Will. There was no power to terminate the trust. Husband 2 has now died (within 2 years of wife) and the two estates will aggregate.

Is there anything that could be done to make use of the NRB from husband 1 at this stage?