What to call a half-sibling?

As you all know, I'm rather intrigued by half-sibling relationships. Even before Joel and Abby arrived in my life, I thought it would) be cool to have a half-sibling (I never wanted a step-sibling, ironically...maybe because you can still call a half-sibling "brother" or "sister" and you really can't with step-siblings.) Since I didn't get to have one, I'm excited that Joel does! We've decided that we'll tell him that Abby is his half-sibling for learning purposes, but he'll refer to her as his sister. I came across this blog post while doing research for an article. I thought I'd share.