No, they usually give it to a close family/relative that is single. And only resort to a married person if the family really want to keep the DIL and the children.
If you continue watching the video part 6
At 7:50
The deceased brother’s wife is with sue and his wife in America Matter of fact, she has always been with sue in part 1 of the documentary Since his brother pass
https://youtu.be/xFvt3QaLajQ?si=NKO_NVISf_kElXXWThe DIL will get pass down to a brother or family member
So she stays in the family clan
Otherwise she can always start new too
But they will try to get her to stay in the family first always