Create calendar event based on another event?

Is it possible to automatically create or update a calendar even when another, specific item is created or edited? I’m trying to automatically track a schedule and I’d like to have a a pre-existing event modified to be a certain number of days from another completed event. Events would be on the same calendar.

So, basically I’d like to have Event B updated to be 10 days after Event A is added or edited. The reason is as Event A could be completed a day or two early or later than scheduled, so I’d like Event B to reflect the time.