Thereby, of course, hangs a fairly fundamental problem. The technical logic is fine, but in practice, why shouldn't an employee have two managers? I'll admit it's not that usual, but if a managerial position is a job-share, you've got two part time employees who're both legitimate managers to the whole of the subordinate team. It might be difficult to map hierarchally, but we can't force a change on the business process just because our software can't cope with the business's needs.