I’m not entirely sure I understand the question. FWIW, when I plot things out, I paint with pretty broad strokes. Just sit down and write the scene and see what happens. I’ve never plotted below the level of “X does this thing” to begin with. Even if it sucks, it’ll be on the page and you can move on.
On a rewrite recently, I was having a terrible time because of POV considerations and finally just cranked something out, knowing it had all sorts of gnarly head-hopping and other problems. Once it was actually on the paper, though, I could see how to address the problems. If I tried to wait until I thought I’d solved them all to write anything, I’d still be waiting.
eta — on rereading your post, there may be an additional problem. Introducing people and their relationship isn’t something happening. You probably don’t want to write the scene because there isn’t a scene to write yet. You need to have something going on, and just saying “here are the characters and their relationship” isn’t going to get you there. I’d either look at the information and see if it can be worked in later in the story, or come up with something significant for them to do in a way that introduces them and their relationship. But you need something going on to have a scene, and it doesn’t appear you have that.