أحسن الله إليكم Females cousins will be visiting for lunch, my father being their mahram, if my brother sits with us,is it impermissible for me as a female to be there? i told them it is free mixing and haram. father is persistent. can i sit as i am not the one freemixing? or is this endorsement?

Ustadh AbdulAziz al-Haqqan

If your presence prevents or reduces that which is forbidden, then it is better to be present. If it your presence does not do so, then do not attend. Excuse yourself nicely.