A Muslim is forbidden to
marry the step-daughters of the wife with whom the marriage is consummated. He will be considered as a Mahram to all her daughters. Allah (Exalted be He) says:
Forbidden to you (for marriage) are: your mothers
until He says:
...your step daughters under your guardianship, born of your wives to whom you have gone in
However, if the marriage is not consummated with that wife, he will be regarded as a non-Mahram (a marriageable relative) to his step-daughters. This is based on the Ayah (Qur'anic verse) in which Allah (Exalted be He) says:
...but there is no sin on you if you have not gone in them (to marry their daughters)
(Part No. 18; Page No. 219) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.