Do you want to redefine the behavior of the Save Grid Filter/Restore Grid Filter commands in the filter box's Tools menu?
Theoretically we can provide 2 corresponding events for that - say, BeforeSaveGridFilter and BeforeRestoreGridFilter. They can have a Boolean parameter like DoDefault to enable/disable the built-in functionality.
Or it can be a new Boolean setting in AutoFilterManager - for example, CustomSaveRestoreGridFilter. If it is set to True, AutoFilterManager would raise 2 new events, CustomSaveGridFilter and CustomRestoreGridFilter, in which you could implement your custom save/restore grid filter operations.