Which is more rewarding: performing Umrah on behalf of deceased parents or on behalf of deceased children, given that Umrah has already been performed for them previously?

Performing Umrah on behalf of the deceased is permissible, and its reward reaches them. Parents have a greater right to righteousness and kindness than others, even if the deceased are their children, due to the immense nature of their rights and the great emphasis placed by Islamic law on being dutiful to them. Therefore, parents are given precedence over children in righteousness after death, and the mother takes precedence over the father.