This style of numbering does not fit with the concept of OLH. A user can open any topic and jump to others. It's rather like a website where you read just the pages you want rather than reading in a linear fashion.
It could be achieved within a topic using a multi-level list but all topics would start at 1. You might be a way of cheat the start number manually.
See www.grainge.org for RoboHelp and Authoring tips