Thank you for that additional information, that will be helpfull in allowing me to advise you today.
A mirror will is not a “joint will”, they are two separate things.
A Murrow will, like you have, looks the same, has the same legacies etc, but there is nothing to stop one person changing the will when the other has died.
A joint will, is not used that often, but is as it says “joint” it is one single document that is created for both partners and is signed by both it is like a contract that cannot be changed.
So, a “joint will” is one option.
Another option is to make new wills, that would leave a “life interest” in the property and estate to the surviving partner, and when their life interest ends, the estate goes to the daughter.
That is the most common way these things are done.