Just gave this some more thought and of course you are trying
to insert a Home button in the topic to call the default topic in
the parent but, I suspect, believing that will open the full TOC.
It will not. You need to link to the startpage of the parent as
that will open the full merge with the default topic.
I think it will also leave the CSH topic open which is messy.
Better to call the CSH help so that it is opened using the
startpage#target method.
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