I don't know. I think the one you get a war table operation for is the one the game assumes you want as a candidate (by implying you'd support her through dialogue options). I got a war table operation to support Cass on my first playthrough and got her as Divine even though I didn't do the operation (was supporting everyone and wanted to see who the game would give me without me influencing it).
Third playthrough I only supported Leliana who I wanted, but I never got any war table missions for any of the Divines, and I ended up getting Vivienne (I was quite surprised).
Only playthrough I got the Divine I wanted was on my second playthrough with Vivienne, and I think that was just luck. It's your overall choices throughout the game that influence who becomes Divine the most rather that who your inquisitor supports.