Wishy - Save File is not connected to LocalStorage, Arrays or any plugins. I think I am starting to get your point. What you need is a boolean or variable that tells your game that if your game is updated and overwritten. Actually the event above will actually help and I will modify it below:
-Make a global variable named "Has_SavedFile"- with number value of 0.
-Make a global variable named "Version"- with number value of 0.
-Make a LocalStorage Key named "Version"-
-Make a LocalStorage Key named "Has_SavedFile"-
*On start of layout
------> Local Storage.Check Item Exists ("Version")
------> Local Storage.Check Item Exists ("Has_SavedFile")
*LocalStorage on Item Exists ("Has_SavedFile") or * LocalStorage on Item Set ("Has_SavedFile")
------> Set Global Variable "Has_SavedFile" to LocalStorage.ItemValue
*LocalStorage on Item Exists ("Version") or * LocalStorage on Item Set ("Version")
------> Set Global Variable "Version" to LocalStorage.ItemValue
\\*Let's say that the new game update version is "1". If the key "Version" is only available in the update, the key "Version" will be 0 in default**On Item get ("Version")
*Start of Layout & *If Global Variable "Version" < 1
\\*Detach the save file of connection with your game until it is overwritten by a new one.*\\
----------> Set LocalStorage Key "Has_SavedFile" to 0
\\*Update the values*\ ---------> Set LocalStorage Key "Version" to 1
*If Global Variable "Version" = 1 & On Save
----------->Set Local Storage Key "Has_SavedFile" to 1
*If Global Variable = 1 & *Global Variable "Has_SavedFile" = 1
------------> Enable Load Button
*If Global Variable is not equal to 1 & *Global Variable "Has_SavedFile" is not equal to 1
------------> Disable Load Button
The trick here is to deactivate the load button if the game is updated and not yet overwritten by another saved state. Hope that finally helps.
If my event above isn't clear then I can send you a .capx if you like.