So, the sisters are Katie/Jenna and Elaine/Bella.
The blondes are Debbie, Jolina, Crazy Church Lady ( I forgot her name).
Key words: Introduced, that means MC didn't know them before. Beach: Not beach house.
Closer with the sister than MC: That means MC and she are still not that close.
So, MC was with Jenna when they met Jo. To me, that doesn't mean Jenna "introduced" them, to introduce someone you need to already know them. Jenna mentioned specifically it was their first time at the shop, they didn't know each other. So therefor, it is not Jolina.
Right after that stuff, Katie introduces MC to Debbie. So, she already meets the most basic requirement, the issue is she doesn't know anything about MC. The gold digger would need to know something about MC, it's the only way they could be the gold digger. She is probably too young too.
Bella introduces MC to Theresa. She is closer to Jolina since MC and her just met. The issue here is she doesn't have any connection with MC either...but she is also crazy so who knows.