extra judicial settlement on untitled lands

SCENARIO: My great grandmother (GGM) owned 1/7 share in several lots as evidenced by "Order of Issuance of Decrees", but these lands still do not have land titles up to this date. My grandfather inherited from my great grand mother and also bought the shares of other heirs in said lots, resulting in his owning 5/7 share of said lots. My grandfather and grandmother passed away more than a decade ago intestate, leaving behind 10 children. One of the 10 children also passed away intestate leaving a wife and 7 children.

How do we go about settling this extra-judicially since these are yet untitled lands? I understand that the BIR requires payment of estate taxes within 30 days but this was not done by my parents, uncles and aunts, what penalties are to be expected?

in 2001 we made an extra judicial settlement with special power of atty, 5 of my siblings sign in this legal document, now is it still valid this yr if 3 of my siblings is already dead? do i have to make a new documents? the p[rincipal is also dead,ty