Would dating my friend's girlfriend's sister be awkward?

This has kinda been on my mind lately. Anyway, I've been friends with this one guy for quite some time now, and he lives with his girlfriend and their 5 year old son. They want to get married here soon, but for now, they're just boyfriend and girlfriend, but also parents. The girlfriends' sister just moved in with them somewhat recently. I had met her before at the kid's birthday parties, but I never knew her that well since she lived in another state, but now lives closeby to me and with them. I think she's really cool, and I do know she's single. If she wasn't my friend's girlfriend's sister, I would definitely ask her out without question and give her a chance. But since she is, that could complicate things. I would still want to be on good terms with those other friends of mine since I do consider his girlfriend a friend of mine too. I believe the girlfriend is very smart, has a great sense of humor, is a great mom, and is easy to talk to, and I think her sister could be very similar. What do you think?

Would dating my friend's girlfriend's sister be awkward?
Post Opinion