No they should be separate.
Most helis have a governor, so you only use the throttle during engine start then set it and enable the governor to manage it through flight. You can even use the mouse to control the cockpit throttle in this case.
If you are flying an old design of heli without a governor then I can’t really help. You really need a control that let’s you manipulate collective and throttle independently and precisely using only one hand. Obviously a real hardware collective is perfect in that role.