Simple Question: Parenting Prefab Clones

I am rather new to Unity, so perhaps this is a stupid question. I am attempting to instantiate dominos. What I am trying to do is instantiate the domino from my domino prefab, and then instantiate the number pegs ontop of it, and parent the pegs to this domino. Of course, I wish to instantiate the whole list of dominos (zero zero dominos all the way up to six six). But I have no idea how to parent an instantiation to an instantiated child. Perhaps there is a better way of doing this, like importing domino models or something, but I’d rather do the more difficult way so I may learn more. Currently I do have all the dominos and respective pegs generating correctly. I just need to figure out how I pair them as parent and child.

I guess a better question is how do I reference clones?

Please carefully take a look at all the examples in Instantiate documentation. Unity - Scripting API: Object.Instantiate

Instantiate returns the object which it creates and do whatever you want to do with it. You want to parent the pegs to the instance to not the prefab from which you create the instance.