whom is NOT grammatically correct in that clause. (who is also incorrect). should be whose. who(m)(se) is NOT the object of the clause, it is the subject. so it is NOT whom. but it IS possessive, so it should be WHOSE.
whom is NOT grammatically correct in that clause. (who is also incorrect). should be whose. who(m)(se) is NOT the object of the clause, it is the subject. so it is NOT whom. but it IS possessive, so it should be WHOSE.