Preventing chained callbacks from switching dropdown to original value

The crux of the post is that I want my dropdown options to be chained together because the data is structured in a multiple nested dictionary. As such, each option should be related to another option (which is how it currently works and how I want it to work). What I don’t want though is a dropdown selection to fire off a different callback, setting the value of another callback to the initial value, when the user didn’t actually want to change that dropdown option.

Have seen some comments about using State instead of Input for my callbacks, or using PreventUpdate, but not exactly sure how those need to be implemented in this case. Any help would be appreciated.