If you have both at the same time...just isolate them in a room with a fan, and BAM seeds...

If you want to collect pollen when sacks open, then use a little single beer bag and put it over one of the Male Top's that have active open pollen sacks and shake the limb while choking the bottom of the bag. Then store in fridge inside plastic bag to let excess moisture dry out, then into freezer...When you want to use it, thaw it out and put bag over female budding in early flower, and Bam! seeds

By the way, I am moving this to Advanced techniques where it belongs...peace