Say that there are two adult children who have, most sadly, lost their remaining parent. One adult child has begun a wrongful death lawsuit.

The other adult child has become the personal representative. The adult child who is the personal representative doesn't like the law firm that the other adult child has chosen and, as a result, has not "signed on". According to the law firm, this personal representative is a "use plaintiff" (whatever that is). The lawsuit is in its discovery phase (if that's the correct terminology). The law firm sent the personal representative a number of questions that the personal representative finds abusive (and will never answer, under any circumstances). Normally, the personal representative would have fired the law firm. The personal representative chose to not fire the law firm out of loyalty to the personal representative's sibling. Unfortunately, the law firm has now demanded answers (which it will never get) and issued threats (to the personal representative). (You know what they say about good deeds.) Can the personal representative fire the law firm? If so, how, please?