Thank you teachers and fellow seekers. I meditated on what you said here and I have come up with:
Push is good. I will remember it for the future.
I have scrapped the grepping of lists thing and am implementing it as a hash table of hash tables as Davorg suggested.
I don't understand Davorg's code, but mine works, even though I'm sure it's obviously written by a neophyte.
Each response was thoughtful and informative. Thanks to you all.