Don't confuse being beneficiary with being executor. My understanding is that you can name anyone you like, usually with their agreement, to be executor. The executors role is just to ensure that the estate is distributed in accordance with the terms of the will, and the family cannot challenge the selection of executor except under the most extraordinary circumstances. Whether you choose to do the work yourself or farm it out to a solicitor, charging the estate, is entirely up to you. If the estate is simple (i.e. no property and cash/savings) then it's a simple matter to do it yourself. If there are any trusts involved then it's a different matter.
If the daughter is concealing a will, or if she is trying to circumvent a valid will, then she is committing an offence. There is plenty of info on the web. The family may be able to contest the will if the estate is being left to others, but there is no right in the UK for offspring to inherit from parents. For example, one of my aunts married for the first time in her late 40s. She owned her home outright and lived there with her son. Her husband was 15 years older than her and she was persuaded to make a will in favour of her husband. When she died suddenly in her mid 50s everything went to the husband, who sold the bungalow and disappeared with everything - including all her personal family stuff. Her son, who by that time had moved out and got married himself, got absolutely nothing.
If the daughter is concealing a will, or if she is trying to circumvent a valid will, then she is committing an offence. There is plenty of info on the web. The family may be able to contest the will if the estate is being left to others, but there is no right in the UK for offspring to inherit from parents. For example, one of my aunts married for the first time in her late 40s. She owned her home outright and lived there with her son. Her husband was 15 years older than her and she was persuaded to make a will in favour of her husband. When she died suddenly in her mid 50s everything went to the husband, who sold the bungalow and disappeared with everything - including all her personal family stuff. Her son, who by that time had moved out and got married himself, got absolutely nothing.