There is a one to one relationship between my webMethods Server and an IS server instance. It is not possible to point a single my webMethods Server to multiple instances.
I have talked with webMethods about this. Their solution is to use one monitor database on the backend and have the my webMethods Server point to that with all of you IS instances using the same backend database.
I have not tried that and I am not planning too. There is a feature request in to make it possible to do what you are talking about in a future release.
#webMethods#webMethods-General#Integration-Server-and-ESB#webMethods-Architecture