Is it permissible for me to marry the daughter of my cousin knowing that I am already married to my cousin's sister?
(Part No. 18; Page No. 244)
It is not permissible for you to be married to the daughter of your cousin and her paternal aunt.
The Prophet (peace be upon him) forbade marrying a woman together with her paternal aunt, or marrying a woman together with her maternal aunt
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.