I think my folks handled it well with all of us who had relationships in college and grad school. They were welcoming enough of anyone we wanted to invite to any meals with the family but not effusive. They also allowed us to have serious SO’s fly to our family home and spend some time as guests. (It was only males and they would sleep in the boy’s bedroom with our brothers.)
My folks never met the families of our SO’s until or unless there was an engagement. It worked for everyone.