CHM format supports merging. Basically it's very similar to the WebHelp. You nominate one project as the "master", then add child projects via the TOC. At run time, the master project looks for and includes any child projects in the TOC and presents as a single project.
But that's not what you asked, is it?
If you want to create a singular CHM file, you need to Consolidate projects. Not merge them. In order to do that, you take one of the projects and import the topics and images from the other projects into this one. You would then be able to create a single CHM of all topics.
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You said you used to deploy webhelp. That should be published to a server. Just wanted to make sure you are aware CHMs do not run happily on a server so could that be an issue for you?
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But, the situation this is:
HomeProject1 and HomeProject2 call ChildProjects. If I imported documents
ChildProject into HomeProject1 and HomeProject, they are duplicated.
This documents exporteds directly in client, not in server.
One more question ...
My project does not directly use the TOC of the child project, but has isolated topics that reference the child project.
When these files are accessed from the path directly or Browse Sequence tool, the toc isn't
synchronized. There is a alternative to solve this problem?