Versions 18.104.22.168 and 1.6.x.x/2.x can exist together as the assembly names are different. You will not have to do anything and if you look at the GAC and the Syncfusion Public Assemblies folder (C:\Program Files\Syncfusion\Essential Suite\Assemblies) after installing version 22.214.171.124 on a machine with say version 126.96.36.199 installed you will see both the old and new assemblies:
version 188.8.131.52: Syncfusion.Grid.dll
version 184.108.40.206: Syncfusion.Grid.Base.dll, Syncfusion.Grid.Windows.dll
So your older applications can link to the 1.6.x.x version and you can build newer applications that link to the 3.0 version.