Elder Brother Being Uncooperative With Regard To Ancestral Land

We are 5 siblings. Our father, who died intestate, inherited 10 acres of land from our grandfather. Out of 10, our father gave away 6 acres to our eldest brother via a gift deed when he was still a 'minor.' The 7/12 and 8a transcripts (utara) of the 6 acres is in the brother's name. While the 7/12 and 8a transcripts of the remaining 4 acres is our father's name. Since all 5 of us are heirs to our father, we proposed to him that we do the necessary paperwork to get all our names on the 7/12 and 8a transcripts. But he has refused to cooperate. So, Is our brother the sole heir to the 6 acres that was gifted to him or can the rest of us also claim equal share in it, since the land is ancestral. Can a gift deed, even if it is registered, be deemed valid if the person receiving the gift is a minor. What should we do in order to get our names added as heirs on the 7/12 and 8a transcripts. As a side note, I'd like to add that we're Christians. All your help is greatly appreciated. Thanks.