1. Dear Adele, it is perfectly permissible in proving a will, to prove a copy of the will, even if the original will cannot be found. Normally, the proving of the will would be the job of the executor of the will, but given the behaviour of your older brother, you may need to also issue a Contentious Probate Summons to remove him as executor, particularly given his mental problems. However, if there is someone else named as executor they can prove the copy of the will. However, you may still need to remove your elder brother as executor if he persists in being obstructive.
2. The ability to prove a copy of the will is available to avoid situations such as the one you have outlined where there is an element of hiding the will and not being forthcoming with the deceased's affairs. Be aware that your brother has no lawful authority to prevent the other siblings from accessing the house. being executor only gives him power if he extracts a Grant of Probate. As he has not done so, he has no power to prevent other people having access to the house. So, here he is acting out of line.
3. I would advise you to get the other executor to the will - if there is one named - to prove the copy of the will and to proceed to probate. Hire a solicitor who will look after your interests and get the will proved and your brother removed as executor as soon as possible. Don't let your brother hiding the will prevent the estate getting administered.
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