Mate, we've known each other (virtually) for a long time, and you've always come across as a stand up kinda guy, like, a lot of guys on here should be on some kind of predator register but I have always thought you're a legit decent guy, it doesn't surprise me that a ml would intro you to her sister if she thinks as I do. So I have no doubt in my mind that while others are saying do both sisters and all that, you're not about to fuck up a potentially good thing with short-sightedness, but at the same time you're not going to put all your eggs in the one basket for something that may not go much further.

I guess what I'm saying is you're a good enough bloke to make the best call for all involved.

Enjoy dinner, take a cake from one of the Korean shops in Eastwood (or the Taiwanese bakery in Castle mall is good too) and a nice bottle or two of whatever tipple you think the girls can handle and the BF might enjoy. Perhaps a champagne and a good red, or the red and something for after dinner...