What should be done with an unislamic will?

As Salaamu Alaykum
Mufti, I am currently a practicing attorney and have the following concerns which I would appreciate if you would advise me on:-
I am often instructed to wind-up deceased estates for muslim clients. What should I do when the deceased passed away with an unislamic Will? Should I continue to administer the estate bearing in mind that the distribution will be against the rulings of Islam?