the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
The stepfather is not at any time to be considered the father of her children from another husband. He has no parental rights on them.
The stepfather has no power of guardianship over her children from another man.
However, he will enjoy the general rights of kinship and relationship both before and after divorcing the mother.
Source: Islam Today