Sounds like basic Mystery Method from what you're telling us. It was right to approach the set and focus on the UBF's, this disarms the target and gets the friends approval before making the transition towards the HB. I am horrible at negging, but you could neg the target offhand then, focus on the friends for a bit more building value in their (and thus the HB)'s eyes, then you can say something like "I've been ignoring your friend, do you mind if I steal her away for a moment? I promise I'll bring her right back

" They'll say yes because you've already built that value up for them to approve of you so then you can take the target to the side, and continue with the seduction from there.