Darrin--as seen throughout the series--had to begrudgingly tolerate Samantha's family popping in, since he had no means of preventing their visits. Sure, he would yell, threaten to leave or demand Samantha to ban her relatives from the home, but his desires were largely ignored.It always surprised me that other witches liked Darrin because he really did look down o them and their culture, they were the embarrassing in-laws to him and he couldn't wait for them to go away.
He married Samantha and expected her to fit into his mortal world but he never made even the slightest attempt to fit into her world. I'm not saying he should have moved to a witch town but did he ever celebrate a witch holiday with Sam or attend any of her family functions?
About his participating in family functions...well, when Samantha was named queen of the witches, he did swallow his controlling nature a bit as she handled the affairs of her people...in the Stephens house. Darrin also travelled with Samantha and Endora to Salem for the Witches' Convention, but I cannot recall if he actually participated in any of the functions.
(FYL came out in 1985).