I saw this question in one of our internal maillists and I sometimes also get the question why you aren’t able to select another MP than the one where the custom monitor has been saved.
Why is this and is there a way to place them in a separate MP?
This is happening because the monitors are defined in an unsealed MP. When you create an override for a monitor and store it into a separate MP, under the covers there is a reference created from the override MP to the MP which defined the monitor. There can only be references created to sealed MPs. In order to create overrides in a separate MP, you need to first seal the MP which contains the monitor.