Shinamae I would recommend that you give a PoA to all your children and stating that they can act severally as well as together. That means that your daughter can look after your affairs either on her own or in consultation with her siblings, and if anything happens to make it difficult for her to act for you (accident or illness etc), the others can take over without any problem.
A friend's mother did what you suggest and when she developed dementia her daughter exercised the PoA and managed her mother's affairs. Unfortunately her daughter died suddenly and the PoA was void.
To take over the responsibility of looking after their mother's affairs, her brother had to go through the Court of Protection, which was expensive and then had to get every item of expenditure approved by the court. It was a nightmare.