It is not a good idea to appoint co-attorneys in fact unless they get along well and both have the principal's best interest in mind. If they disagree here are some possibilities to arrive at a solution:
There are states that it is necessary but there are cases that you do not need an assistance, or even require power of attorney.
A power of attorney has absolutely nothing to do with an estate. All power of attorneys expire on the death of the grantor.
"Attorneys general" is the correct term because "attorney" is being used as an adjective to describe the type of general, just like "doctors' office" refers to an office for doctors. So, the possessive form properly applies to "attorneys."
The Power of Attorney has no rights over a parent of sound mind. The power of attorney is given by the parent and can be withdrawn at any time. And the power of attorney automatically ends upon the grantor's death.
The power of attorney represents a living person. The durable power of attorney will end with the death of the grantor.
A power of attorney expires on the death of the grantor. The executor needs a letter of authority.
Generally, that language means the attorneys-in-fact can sign together or alone for the principal.
There are two main types of powers of attorney, durable and nondurable, and two subclasses within those types (immediate and "springing").
If the Attorney In Fact dies, then the Power of Attorney is null. In most states this means that if the individual is incapacitated the next of kin can have that person adjudicated incompetant in Probate/Family court and can take over the affairs. NB: a Power of Attorney is a document. An Attorney In Fact is the person to whom a power of attorney is granted.
The power of attorney represents a living person and a living person has no obligation to share or show a will. The power of attorney ends with the death of the grantor and they have no say in the estate.
In a matter of speaking, an enduring power of attorney is the power given by someone to a specific person or persons (usually attorneys), to manage their financial affairs. Most of the time, this is done when someone is not capable of handling their day to day situation, but sometimes it is done in the short-term when a person is traveling.
The fact that there is a will doesn't matter. The power of attorney is valid until the death of the person it is associated with, or it is revoked, whichever comes first. The guardian is responsible for taking care of the individual. If the person handing the money (power of attorney) can't agree, they will have to go to the probate court for resolution.