inheritance

As Salaam Wa alaykum

We are currently involved in an issue in pakistan, (Dadyal AJK).

My grandad had some land and houses. He had divided it between his 4 sons when he was alive. He died in 1984, after death, apparently according to custom of law in Pakistan the Estate has to go in name of oldest son(Karamat Hussain) and then he later divides it amongst the rest of the brothers. This was not divided officially through court but rather just by mouth. They have never ever done a drawing of anything and said this belonhs to this brother and this belongs to the other brother.

My dads oldest brother Karamat Hussain has a son in the Uk who is staying illegally and has no intention of going back to Kashmir.

Now in 2017 my dad was going to build on his part but his oldest brother Karamat said you cant do anything as the whole land is on my name and my son in the Uk has to be with me for me to divide it, i can not act on my own he has to be with me for me to do any signiture.

Now is this even possible?

That the inheritance goes to the oldest son automatically in his name, he looks after the estate and  can take charge of all of it??

Does my dads oldest brother’s son have to be in Pakistan to sign for his dad(karamat)?

Can my dad not just register his piece of land on his name? What does he have to do?