My MIL has been married 3 times, the 3rd time when she was in her 80s. For the 3rd marriage, she didn’t change her name to her married name for everything, rather she must’ve started the process of doing that with certain institutions, but either didn’t get round to doing the rest of them, or changed her mind about doing the rest of them. So, her passport, driving licence, and banks are in her 2nd married name, but HMRC and her pension are in her 3rd married name. 3rd husband is still alive and they are still technically married, but he has been in a home for the last couple of years with dementia and is not compos mentis.
She wants to revert to her 2nd married name for everything. (We had suggested divorce, but this did not go down well). I wondered if she could just do this via a deed poll of some kind?