B-Sweet I came to answer your question because I use to have a wing down here with that name. Opinion openers are good to use in field but you don't have to ask them the same question. Also, you can use a direct or situational opener to start the conversation. Then use an opinion opener like a conversation thread to stack with. Everyone asks questions and I have never been called on the spot. I will ask a common question though. Since I do a lot of Online stuff I ask girls, Have you ever put up an online profile to meet people? What do you think of Online Stuff? Since there are conflicting veiws I may say, "Come here...(walk her to previous set) Introductions...She thinks that....& You think....Who's right?" There the set is merged.
This is one of many ways to do it. Find a conversation topic that is good, then get different view points. I've asked a girl a question in set and said, "Ohhhh hold that thought....I got to grab someone." Went and got the other girl or set brought them over, introduced, told them what I asked her, then said, "Okay so what do you think?" Let her say her words. Then ask the other set their opinions.
When you merge sets you are the man and the life of the party! You need a good energy level to do it, but its great at building your social proof. Also, a great way to isolate a two set is to merge the obstacle to another set then isolate the target.