We are currently looking at cleaning up some MSM configurations and found that when breaking inheritance on a page property on a Live Copy page, that this creates an additional cq:LiveSyncConfig node under jcr:content of that page. All properties - except cq:master, which points to the respective Blueprint page - are empty.
We want/need to understand why this additional cq:LiveSyncConfig node is created.
Our understanding is that the breaking of inheritance of a page property is reflected by:
A cq:propertyInheritanceCancelled property on the jcr:content node, with the property as a value
jcr:mixinTypes is updated to add the cq:PropertyLiveSyncCancelled
These properties should be enough, what is the additional cq:LiveSyncConfig node for? And when deleting the additionally created cq:LiveSyncConfig node, all of the inheritance mechnisms seems intact and functional.
Note: Re-instating inheritance on a property does not delete the cq:LiveSyncConfig node.
We also found that this node is only created when the page properties are edited via the Touch UI, but not when editing on Classic UI.
We reproduced this behaviour with an Geometrixx site and also on AEM 6.1 SP2 without any CFPs installed.
If you look at this old documentation Multi Site Manager for Developers , the cq:LiveSyncConfig node is created as part of the cq:LiveSync mixin. It can have properties such as cq:isDeep, cq:master, cq:trigger. Also here's a newer link around the 6.1 timeframe that provides essential the same information Adobe CQ Help | Troubleshooting AEM MSM issues . The node is part of the mixin type and adds configurations to help with the sync. This information is needed if you ever re-establish the linking. It's fine if the linking continues to be broken but you may or may not have issues when relinking the content (I haven't tested this).
Also it appears that the cq:LiveSyncConfig node can have a cq:excludedPaths property in cases where you have moved or renamed the blueprint MSM Faq.
I'm not sure why your able to cancel the linking and relink without issues. It may be that you aren't hitting one of the cases above.