They will try to get the next of kin according to the will. I assume as your his husband that you should be the closest of kin
Your brother's daughters are your nieces
Your daughters husband is you son-in-law.
4 daughters, 3 sons.
The next of kin is usually a child and not a sister. For example, if a mother passes away, the next of kin would be her husband and then her children.
They are still your grandchild even if only by marriage and not blood
Yes, they are brothers.
Yes, they are brothers.
The grandchildren are.
Not if you are the mother. cousin, or basically family blood.
The brothers of your husband are your brothers-in-law.
Your grand daughter's husband is your grandson-in-law.