The power to sign dissolution papers would depend on the power of attorney - unfortunately exactly the information you don't have. If I was advising the daughter I would recommend that she apply for a conservatorship of her mother's estate and for a specific power to dissolve the marriage. Then it would be up to your father-in-law to determine if he wanted to object.
Best to you and your family.
This raises a very interesting issue. Whose “emotional reasons” are we talking about? A conservatorship would provide the daughter with power of decision making for her mom. I would be very surprised if the power of attorney contained an expressed power to enter into a dissolution proceeding. What does the husband think about all of this? Unfortunately, attorneys will probably have to get involved.
Whether or not it’s a waste of time and money is better answered by your father in law consulting an attorney.
Best of luck to you.
If you found this answer helpful, let me know by clicking the "thumbs-up" button at the bottom of this answer. It’s easy and appreciated.
This response is intended to be a general statement of law, should not be relied upon as legal advice, does not create an attorney/client relationship and does not create a right to continuing email exchanges.
I do not expect the POA agent may not sign the court papers. However a "GUARDIAN AD LITEM" can be appointed and is less expensive than a conservatorship.
Here is a sample of one form use to have a guardian appointed. The Guardian Ad Litem is only guardian for the court case.
The Guardian must use a lawyer, and may not appear in court Pro Per.
Sign up to receive a 10-part series of useful information and legal advice about the divorce process.