When grandpa and grandma have always been a swinger couple and grandma still looks hot despite her 60 years (see fan art "Gilf challengee"). And Grandma realises that Sophia and Sam have more in common than just a teacher/student relationship, she could offer to distract Liam so Sophia can spend time with Sam.nice we are going to meet Sophie and Patricia Parents!!!!hot granny and grandpa?
I know, very speculative and not very plausible but it doesn't matter anymore anyway.