Is it obligatory to seek permission from the person who bathes the deceased before washing the corpse, and is there a sin incurred by washing it alone?

It is permissible for a woman to wash her female relatives, and she has more right to do so than unrelated women. There is no requirement to seek permission from those who undertake washing the deceased. There is no harm in washing the deceased alone if she is capable; otherwise, it is legislated to seek assistance from some relatives. The presence of those whose help is not needed is disliked.