Per Eric's comments, yes you can split off a "piggy back" stave or billet and build a bow with them. Once you split them off, make sure you seal the back as well as the end. Without the bark, the back of the piggy back stave will check quickly, so get it sealed. I've used glue with good success but shellac will also work very well......two coats perhaps. I'm getting ready to start a bow with piggy back billets from a 110 year old hickory. Nice wood :-)