Script to convert absolute links to relative

I'm working on a manual in RoboHelp 11, and we're working on going from a WebHelp Pro output to Responsive HTML5. While we make this transition, we're making some updates throughout the documentation, and the issue of creating relative links has been one we've struggled with for a while. Currently, all of our documents are created in Word and then linked to the project. Wherever there are related help topics, we've linked them in the Word doc. The problem with that approach is that when we make this move to a different project (or if in future a document is moved) all of the links will need to be updated, because they point to the absolute location rather than the relative location of the topic. We've tried creating relative links in the Word documents, and it doesn't seem to work. We can't create the relative links in RoboHelp because we would lose those changes every time we update our linked documents. I'm hoping to find someone who has written a script to be run before the single source layout is generated that will find all absolute links and convert them to relative links, or even if someone could point me to some tools that may help me write one. Any help is much appreciated!

Thanks!

Cassandra