argh.. Looking for this function right now.
It makes sense that scale and centring could/should be independent for this second option in the map series.
I'm currently attempting to show a regional NRM boundary with a map series of threatened species within our region. Ideally I want the region to stay as the focal point on the map and only cycle through the lines (or polygons) defined by the map series, centered on the whole NRM region not just the current map feature.