issue solved. there are msdb stored procedures used to create/add servers and groups you enter into your CMS setup in SSMS. the names escape me, but if you trace it you'll find them and then just google them/BOL them for more info on how to use them. i got the the point where i was able to rather quickly add 10s/100s of instances into various groups in seconds, once i'd retrieved a suitable source list of instances to use.