1. Yes, if the sister died whilst the brother was alive, then the deceased sister's children will get her share upon an intestacy (no will) of the brother. So here if the deceased brother has died and had five brothers and sisters, and one of his sisters died whilst he was alive, then if there is no will, the estate will be divided 5 ways, with the four surviving brothers and sisters each getting a one-fifth share and the children of the deceased sister sharing a one-fifth share between them So, if the deceased sister left only one daughter, then this daughter of the deceased sister will also get a one fifth share. However, if the deceased sister had more than one child, then this one fifth share will be divided equally among all her children. I hope this makes sense. If you require any further clarification, I will be happy to help.
If she (niece)didnt receive it at that time now when the last aunt has died is niece entitled to 1/3 when there is 13 other nieces & nephews.
2. There is only a right in relation to the deceased brother's estate. There is no right in a different person's estate if the niece didn't receive it at the time. You cannot transpose or transfer this right to a share in the brother's estate into a right in a different estate, now that an aunt has died.
If niece didnt get her share when uncle (deceased mothers brotherr)died she cant claim any more than the other nieces and nephews now when aunt(deceased mothers sister)dies.is that correct.