Conflicting Keyboard Shortcuts: How to set Hierachy

Dear Support,

I would like to use some keyboard shortcuts multiple times. Depending on the context, I would like to see one or the other option executed. For example, I have *unindent line or selection* on shift  + tab and would also like to place *parameter preview* on the same shortcut. 

Obviously, if I am between parenthesis I would like to get a parameter preview but in all other cases see an unindentation action happening. 

Is it possible to give a hierarchy in which order actions are tried to be performed.

Best, Moritz