Will on a joint property

A is property owner and deceased a decade back. B is the Wife to A. A & B had a children C ( A Male deceased 8 Years back) and D E F ( Female all are married and living at different places. Note : In this issue All are Hindus only. A left some Ancestral Intestate properties to B C D E F(All are married). B recently passed away .But B executed a registered secret will to D's husband(DH) as an executor and said With Out DH consent ie., The Portion what B had a right during her life time( Pl. Remember this is not written any where to B from A)and other portions of Property of A should not be divide Regarding this Will none of the C's Wife E F Knows this at the time of execution. After B's demise this will came into lime light., And B mentioned that will D E F all should not divide the Property without executor consent. Now this D's husband (DH) is not ready to Probate this will. Question is : What type of right B had to execute a will and appoint D's Husband as an executor?. Is this will is valid?.