Legal Question in Wills and Trusts in Texas

You need to review the power of attorney. If the document does not say "this is a durable power of attorney" or "this power of attorney shall not terminate upon the incompetency of the principal." it is not a durable power of attorney and terminated upon your mom's incompetency or incapacity.

If this is the case, you need to consider a guardianship for your mom. If you have a durable power of attorney your are fine.

If the power of attorney does not designate a backup, you may have to consider a guardianship when there is no successor guardian.

Another possibility might be for the attorney in fact to amend the power of attorney and designate designate a successor. I am not sure if that is possible.

I suggest you discuss this with a local attorney that practices probate law.