Hello
You need go for enhancment for this .Please refer below logic
1)Create The Equipment structure which will incldue the all major Equipment and its Dependent equipment as Sub equipment or vice versa.
2)Create Ther Z-Table in which mainatin all above equipments for Check
3)Use the User Exit QQMA0014 - Checks before saving a notification .At this even when user create and tries to save Notification which have Equipmens in Z table will show pop up message.
BR
Rakesh