How do you represent half siblings on a family tree?

Question:

How do you represent half siblings on a family tree?

When you're drawing a family tree in actual "tree" form, two smaller branches represent the parents of a bigger branch. But what if, for example, a mother had one child with one father and then another child with a second father? How do you show that? I'm a rat breeder and I need to show the mother's other "marriages", because the fact that both children had odd eyes means that it's likely that the mother was the carrier of the gene that I'm looking for. But how do you show step-siblings on a human family tree? Please, any suggestions?

Best Answer - Chosen by Asker: We use a different family group sheet for each couple. That is, if Albert and Alice have children, then they divorce, Albert marries Claire and Alice marries Bob, and they have children again, we'd draw up three family Group Sheets - A+A, A+C, A+B. I would use a different family tree for each coupling, in your case.