"BIL has no moral obligation to help me, the split was 50:50 from his parental side. But his share goes on 1 person and mine on 3 people."
I assume this was because the mother's estate was split between the two sons, and your DH's portion came to you. It is unfortunate that the mother did not make further arrangements to bequeath a portion to her grandchildren, but many people do not. Neither of my paternal grandparents did.
I am afraid I really do not see why you would expect your BiL to give you any of his portion of the inheritance.
If half the mother's estate came to your DH, upon his passing, you would directly inherit his entire estate as his wife outside of probate, thus inheriting his portion of his mother's estate. I presume the only way this would not occur is if your DH altered his will to leave the money to his children; otherwise, everything is yours. Full stop.
However, I am unsure where your brother fits into this, nor what he has to do with any administration of anyone's will. Are you saying that your BiL was your DH's executor or his mother's executor, or both? If the mother died first, then your DH's portion passes into his estate, which would then be administered to you by his executor, surely?
That you say your BiL wasn't going to allow you to have anything "directly" makes me think something peculiar may have occurred. If he was the executor to his mother's estate, he had to administer the bequest to his brother as his brother was still living at that point. When his brother (your DH) then passed, it is up to the executor of your DH's estate, who ever that was, to administer his estate directly to you outside of probate.
She wept ... Technically she didn't inherit it from dh. His mother died a few days before him. So 50% of the OPs pils estate went to her. The bil as executor , felt it should go direct to the kids, op thinks its should be kept for the kids.
Surely, she did technically inherit from her DH. That inheritance was owed to her DH's estate when he died and when he did, she, as his wife, inherits everything. It is her money to do with as she pleases, unless her DH made a provision in his will for that portion of money to be inherited by his children.
An executor cannot go telling people how to spend their inheritance or who it should be given to. He cannot tell the op that the parental inheritance should be kept for the children, unless it specifically says so in DH's will and he is DH's executor.