As per usual with legal matters there is a lot of incorrect advice given.
Firstly you need to retrieve the will to see what it says.
Secondly you cannot change someone’s will after they have died.
Thirdly someone still alive can change their will by having a deed of variation or a codicil added which allows a change to a will without having to start again, whilst the person is still alive.
Fourthly if someone leaves you something and you don’t want it you don’t have to have it.
If someone leaves you something eg a gold Rolex watch and the benefactor had got rid of it before death tough you don’t get it.
There is no such thing as a joint will. You may leave everything to your spouse and they leave everything to you but that’s not a joint will.
There are loads of pitfalls far too many to mention here, if in doubt seek proper legal advice because if your the Executor and get it wrong you may be held personally liable for any mistakes.