Handle user permission based on BDM associations

Hi everyone

I'm having a trouble making UI elements and flows enabled based on BDM association between 2 objects. To make clearer I'm attaching a simple diagram showing the association between the elements "operator", "area" and "customer".

diagram

What I want to achieve is that the "Operator" can see in its page ( containing a table ) entries of customer belonging only to its "area" and that this rule should reflect on the workflows also, meaning that an operator cannot start workflows that involve customers belonging to a different area.

Have you got any suggestions to obtain this? some recommendations or good practice that I can apply?

Thank you in advance