Bleeding of the ABS is only required if it's sucked air (hence the advice to keep an eye on the reservoir level).

It's a terrible sinking feeling when you're just finishing a fluid change and you hear a sound like a kid sucking the last of his milkshake from a straw, eminating from the master cylinder - apparently.

In reality there'll be a little old fluid left in the ABS modulator block after bleeding but it will be diluted with the new stuff next time you have a buttock-clencher and invoke the ABS.

When pushing the caliper pistons home, open the bleed nipple to allow the fluid out rather then pushing it back up into the system.

I always change the fluid when I'm doing pads, so I remove the old pads, open the bleed nipples and push back the pistons then fit new pads and bleed new fluid into the system.

It makes life easier if you can remove as much old fluid from the reservoir as possible beforehand and fill it with fresh. Just less fluid to pull through the system. Make sure you get the turkey baster back into the kitchen before Maria notices it's missing though.

Kevin