Mama's Family (1983)

Thelma Harper and her spinster sister Fran open their home to Thelma's recently-divorced son Vinton and his teenage daughter and son, Sonja and Buzz. It's quite an adjustment for everyone, especially the cranky, argumentative Thelma, especially when Vinton becomes interested in pretty, sexy neighbor Naomi and marries her and moves her into Thelma's house.