A man married his deceased brother's widow who had a daughter from that deceased brother. The daughter was raised with her cousins until she reached the full legal age. One of her uncle's sons wants to marry her, so is such a marriage permissible as the girl was raised with her cousins in the same house?
Guide us, may Allah benefit you and us. As-salamu `alaykum warahmatullah wabarakatuh (May Allah's Peace, Mercy, and Blessings be upon you)
If the reality is as you have mentioned, it is permissible for the deceased's nephew to marry his cousin. It doesn't matter if the girl was raised with her cousin in childhood, provided that there is no impediment that affects marriageability such as breastfeeding (Part No. 18; Page No. 334) and the like. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.