The ones I have seen have used Excel Spreadsheets, and they include columns for each character, so their position in relation to everything can be easily seen as well.

I don't mean to add extra work to your idea, which will work and work rather well, I feel, but it might help clarify things.

Another thing I've seen is each storybeat is highlighted in some way to indicate which characters are involved.

But it feels like you're on the right track. I think this coiuld really help clarify your story beats nicely. Good luck!