Invoke Pricing Engine Query

Summary:

I want to understand that how pricing engine will work in the below scenario.

Scenario :

I understand that Pricing Engine will invoke automatically whenever we add a new lines in the transaction.

But after new lines are added and if some of the line grid values are changed by the system based on other Quote attributes, then that time also pricing engine need to be invoked automatically without triggering any action.

Can we able to do that without click on any action (or) action is mandatory to invoke the pricing Engine?