The charity since it is other peoples money are a bit hot on getting the right amount as otherwise they are in breach of trust - in other words they cant say, well we have 90% of the correct amount that is OK for us.
Your friend presumably is doing probate herself for someone who is er dead.
Taxation IHT of half and half wills - half to charity and half to grasping relatives - is somewhat difficult. The charity bit is free - but the relatives then bear that tax burden - as well as their own by a process known as "grossing-up."
She might well say yeah I know sll that.... in which case atta-girl otherwise she needs help.