I have a laptop and used Yast2 to configure an external USB mouse. However, the trackpad became inactive. When I now restart without USB mouse I am in trouble. I used for the configuration: Control Center -> Yast2 modules -> Hardware -> Select mouse model
If you want to operate both external mouse and trackpad, you need to dig deeper: Control Center -> Yast2 modules -> Hardware -> Graphics Card and Monitor -> Graphical Desktop Environment -> Change -> Component: Input Devices
Here you have the possibility to add an indefinte amount of mouses. You should probably test whether you new settings work (with the test button) before you restart. The settings become only active after a restart. Meaning if you want to deactivate your trackpad (because it disturbs you) you need again a restart...