You need to look at the will as a starting point. What does you brother's will say? Obviously, it was made before the compensation was awarded. But, if it states that 'all my property goes to Mary', then Mary gets the compensation money. If it says all my estate should be distributed equally between 'my sisters' then all sisters (legitimate or illegitimate) may possibly qualify.
On the face of it, you should be entitled to an equal share of the compensation. But the contents of the will is very important.