Unique Opens

I'm trying to figure out unique opens for some of our email campaigns. I understand that the delivery table has this indicator, but I'm wanting to break it up into quarters and some of our campaigns go past these boundaries so the indicator isn't reliable for this. My current view is to use nmsbroadlogrcp's event data to set my date boundaries, joining nmstrackinglogrcp in order to get open data, and then counting distinct recipientids to get the number of unique recipient opens. Does this seem logical/correct? I have also read sometimes here of people using broadlogid. Is that more appropriate/why is that used?

Thanks for all your help!