I assume that your sister did not leave a will therefore died intestate. Provided the amount which she left is under £20,000 and there is no land/house/property, this will be dealt with under the smaller state rules were all you will need to do is get a statement sworn that you will deal with the assets in the appropriate way and distribute them accordingly and that you are entitled to do so.
If your sister had children however and no parents the siblings get nothing and the children get the estate equally. They should really be the ones to deal with this unless they are not interested in doing so. If you don’t want to get involved, then leave it behind. You cannot be compelled to deal with it. The only obligation you have is a moral one.
The first call on all the money is the funeral and the testamentary expenses.
However the person who actually organises that is responsible for paying it although they are entitled to recover it from the estate. If there is not enough money in the estate to cover the funeral, then it comes down on that so of whoever organised it. The moral is never to organise a funeral unless you know that there is enough money to pay for the funeral and the executors will pay it.
Ultimately, you cannot be compelled to do anything and if you want to walk away from it, you are quite at liberty to do so. You have no financial or other legal obligation.
Can I clarify anything else for you?
I’m happy to answer any specific points arising from this.
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