[Robert Plant]

It's a waiting game plain and simple. You wait until there's a pause in their conversation, then go indirect.

[The_e_man]

Just last night, I approached a seated two-set that looked to be in intense/emotional conversation with each other.
My open was "Hey is this a super intense convo going on right now or can I join?"

They were very friendly and polite about telling me that they would prefer to speak alone.

[Turnus]

Had this happen to me last night.

Venue was a restaurant in the bar area. Sat down at the bar next to girls in their early 30's. They were in the middle of an intense conversation for about 10 minutes without a break in the action. They apparently couldn't last for more than 10 minutes without taking a selfie which they did and that gave me the opening I needed. I busted their chops about making duck lips and it was game on. Actually started talking to the fat one and ignored the hot one. That worked like magic and text book like soon enough the hot one was vying for my attention. Moved the conversation to talking about the disasters of online dating and kept them entertained with a pretty outlandish story I had. Ended up getting the hot one's number. We'll see if anything transpires.

[satanova77]

These are some of the harshest rejections I have gotten but it has never really stopped me. I think body language is the best tell of when they are relaxed and take a look around to make a move.

[scorpion]

I think this is always going to be a low probability play and not really worth it in most cases. Even by player standards, you've got to be pretty brazen and shameless to hit on two girls who are clearly in the middle of a heart to heart conversation. Interrupting them in the middle of their emotional bonding/support session (that's what these things are for women) rips them out of the comfortable emotional state they were in. That doubles your difficulty right out the gate, because not only are you cold approaching, but now you're starting not at zero ("Who is this guy?") but actually from below zero ("Who the fuck is this guy who just rudely interrupted our conversation? Couldn't he see that we were seriously talking? Is he a social retard or just a tremendous asshole?"). They've both got negative vibes going as soon as you open your mouth.

I think whether or not it works is largely a matter of chance. It comes down to the vibe of the conversation the women were having. If their heart to heart was at a point in the conversation where some sort of distraction would be welcome your approach might have a better shot. But if you try to break in when they're both in a deeply invested emotional state I think you'll crash and burn 99% of the time. So the best way to go about it is to position yourself within earshot and wait for a lull or opening in the conversation where you can interject with the "Excuse me, I couldn't help but overhear..." and go from there.

Personally, I would not even bother with the attempt unless one or both of the girls really caught my eye, or if I didn't have anything better to do than sit around and listen for an opening (i.e. I'm already sitting next to them and eating anyway). It's too low probability to bother with otherwise.