how to start a new baby

When the old 'onion' starts to separate into two parts you will be able to split them apart (wait until it happens without too much of an effort), and then both bits will grow.
You can actually do it from just part of the fleshy leaf and a tiny bit of the base (sometimes even without that), but you need to hit just the right conditions to get the new bulb starting without rot getting in. Lots of fun to try though. derek