This seems like a "relatively simple" venture to me, but at my experience level, I'm highly challenged to get it done. I've touched on a variation of it before.
I have a lengthy Trigger (appx 500 lines) that processes Opportunities and summarizes them at the Account level (useful for our Email marketing and other processes that cannot easily or at all get to the Opportunity data, especially since it's many-to-one).
One shortcoming in it is when an Account is MERGED (let's just say edited to make it more thorough) an Opps from two accounts end up on ONE ACCOUNT, the "piggyback" data is now only from one of those two accounts -- because the Opportunity trigger does not run.
So... what I need to do is have a Trigger, on an Account edit, create a set/list of the Opps, and then run each Opp through the Opportunity Trigger... which is a simple matter of doing an "Edit/Save" on each Opportunity. It doesn't have to "call" the Opp Trigger directly, just create a set of the opps, and edit/save each opp.