Dating : Never been in a situation like this
So a I met a girl at a bar and we hit it off started texting and what not well turns out she is one of my best friends sister. I know your going to be like how did you not know that. So I had been friends with this guy for a long time but he moved away in middle school and would always come visit since he would want to come see everyone from home. So I never met his family until a cookout last weekend and then found out. Anyways it’s nothing serious right now but I don’t know if I should talk to him now about it so it doesn’t look like I’m hiding anything and being upfront but if this doesn’t go anywhere between this girl I don’t want I bring it up unless there’s a future.
just keep talking to her and if things seem to be going somewhere then maybe you can bring it up. if you feel like you owe to your friend, you can talk to him about it sooner .
Does she know it? If she does then yes. If not, only say it causally. Unless you are a total shitbrick or his sister is nuts, then he should be fine with it.