On linux I put them in /usr/local/lib, on MorphOS I can put them in sys:libs or sys:classes, except for those that are updates against those that come with morphos, then I have to put them in mossys:libs or mossys:classes, or put them in sys:libs or sys:classes, but rename those in respective mossys:libs and mossys:classes so that they wont be loaded. And these just some of the locations where libs might go.
Things get easier if you follow that simple and easy fact to not mess around with files in sys:morphos/.
Sure an old Amigan feels like he knows the system and isn't afraid to tinker around, but there is a good reason for that rule.