Option for "save player data" to only update a subproperty instead of the entire data property
Right now in order to save any value to the profile you have to overwrite the entire save/data property and unless you're very cautious and first copy everything in data to save this leads to all other saved data being lost.
This is really bad UX in my opinion, would be great if there was an option to only update a subproperty, for example if configured like picture below the contents of save.deckEditor.collection are uploaded to data.deckEditor.collection while everything else (data.* where * is not deckEditor and even data.deckEditor.* where * is not collection) is kept intact. 
Example mockup.