Elsbeth Lupin would 100% be friends with Laverna and enjoy gossiping with her. She has a pretty terrible reputation though, so that could affect Laverna.

For Myrtle I have Prudence Browne, a 6th year Gryffindor who has decided that she is very against getting married but isn't quite sure how to tell her family that yet. I've a feeling she'd look up to the 'spinster' I also have Eloise Belby who is the Astronomy professor. She's a bitter divorcée who also doesn't like nonsense and is blunt. Not sure if the pair would get on, but I wanted to toss that out there as well.