The property in question bequeathed by a will in favor of the named beneficiaries belonged to one B who is nether your adoptive father nor you were named as one of the beneficiary in the will.
The question is not about the registration of will.
The will need not be registered mandatorily
Even if the B is reported to have died intestate then his surviving class II legal heirs are the successors to succeed his estates.
The surviving legal heirs shall be his siblings who survived his death and not the children of his siblings.
By any chance you dont have any right in the property even for a minor share in it.
Not to discourage you, but the legal position his that you are a third person to the property either by way of will or legally hence any effort or attempt made by in this regard to claim a share may be a futile effort resulting into loss of money, time and energy.
However you may discuss with a local advocate on any other possibility based on any loop holes that may be available when analysing the situation practically.