welcome to the forum!
I assume that your application is based on the widgets using the customized steel appearance (e.g. based on the example WidgetsDemo).
As you probably know, each slider can be combined with a data provider by using the Outlet property. This makes it possible that each slider shows always the actual value of a certain property and that the property is always updated when the slider is changed by the user. By using this infrastructure, every slider can be connected to its own data value.
Now, when you want to have one location where you update the hardware, you can implement a slot method (e.g. DmxUpdateSlot) and connect all sliders OnChange slot method with this single DmxUpdateSlot method. Then, your DmxUpdateSlot method will be called when one of the sliders is moved.
If you want to determine the slider that has changed its value, you can evaluate the sender within the slot method.
Does this answer your question?