Wills.....

[firewatch]

Hi this is my first time on this section, but it is important.
My nan wrote me on friday of last week asking whether i would become a trustee executor and attorney for a trust they have set up to prevent, should one of them go into a home, the local authority taking funds from the other one to pay for the funding of the person in the home.
They are going to sign identical wills which will make them tenants in common.
Im just wondering what would be expected of me? what would i need to sign? im just a little confused and need some strings ntangling.