Inheritance of land of an illegitimate children against the widow & nieces

Hello,
Need help from questions regarding the case of my cousins. They are 4 brothers who are all illegitimate.
Their father had a first wife but no children and their father
had 4 children from my aunt but not married because he was
married to the first wife.Their father acknowledge them
and signed their birth certificates. Their father died and
the first wife to whom he was living had possesions of the house and land titles of their father including all belongings land and cars.
The nephews and nieces of the first wife is actively
pursuing to sell the lands and properties of their deceased
father.
May I know the right of the 4 illegitimate children
and their share on their fathers properties against the widow of their father and her nephews and nieces...may the widow left a will to give to her nephews???


P.S.
from NSO marriage certificate it had negative records.
( awaiting confirmation from CENOMAR) what if it is
negative and the marriage was like pikot style before...

thanks and awaiting your clear response.
Glecon