that is with the previous GSX because the latest one gives me problems.
GSX is not giving you ANY problems. It only makes you a service, telling you *another* addon has caused a problem, forcing the sim to load the wrong Simconnect version. GSX and all our products cannot work with the outdated Simconnect.
I've read all the links you've attached and will try and see what goes where between all the *.cfg and *.xml files although it should not be such an issue if the above mentioned files are correct.
You haven't read carefully enough: the problem is NOT that your XPack-SP2 Simconnect are not loaded, they surely are, also because the GSX installer DOES run the Simconnect installer for you (the one in the P3D legacy folder), but that's NOT the issue.
The issue is, of all 3 Simconnect versions you have installed in your system, ANOTHER addon that uses the old version, has left the sim "stuck" on that one, instead of allowing the system to load then *both* at once, which is what is supposed to be happening with the Window Side-by-side system.
So, rearraning the ORDER or loading, placing the Addon Manager lines in the XML file under %PROGRAMDATA%, it's a way to force the sim to load the Addon Manager *before* this other addon, in order to ensure the correct Simconnect is loaded.
Our current installers, then one released yesterday for GSX and KMEM, have been updated to do this automatically.