You can have whoever you wanted to be your attorney as long as you have full confidence that you can trust that person with all your important information and you will also need to trust that person to make the right decision for you in the future if you were unable to do so.
Your desired attorney must be 18 or over and you are also able to have "back-up" attorneys if your current attorney ever decides that they are unable to successfully complete the role or if they do not have the mental capacity to do so.
A joint attorney is when you have allocated multiple attorneys, this means you can decide how you want your attorneys to work:
You can specify in the lasting power of attorney that the attorneys must act jointly for specific decisions, such as selling a house, and jointly and severally for all other decisions.
Acting jointly with regards to some matters and separately with regards to others. For example property sales would require both but the diet could be settled by one.
However, when making decisions on behalf of you the attorney must adhere to the mental capacity act. This covers the following:
If the attorney fails anyone of these things the LPA can be cancelled. The matter will also be investigated by the OPG and the Attorney could potentially be prosecuted.