Surnames in the Breeniverse

Surnames are a trivial piece of information in the Breeniverse, yet, they can sometimes offer significant information to the plot. The revelation of Sarah's last name "Genatiempo", led to the revelation that she had rented the van that kidnapped Jonas. A listing of Mitch's last name in the LG15: The Last facebook group and subsequent add to the LGPedia helped comment posters discover that Mitch's full name was an anagram for one of Sibylla's agents.

Yet, last names do not always play such an important role. In fact, in the Q&A chat with the cast and crew following the series finale of KateModern, they revealed that the "S." in "Sophie S." did not stand for anything at all. A contest held by Nikki Bower to name Bree's dad led to the canon use of the winning name, "Drew Avery", and the acceptance of "Avery" as Bree's family name.

We know the last names of characters in LG15: The Last, characters that we have only known for a few months, yet we have yet to learn the last names of characters we have known longer. If you had a say, what would you have their last names be? Below are the character names that are unknown. Post your suggestions below. I'm curious to see what everyone comes up with.

(Also, this is not in any way an official contest, this is just for fun.)

Unknown Character Names:

Daniel (Lonelygirl15, LG15: The Resistance)
Jennie (Lonelygirl15)
Gemma (Lonelygirl15)
Lucy L. (Lonelygirl15, LG15: The Resistance)
Virgil (Lonelygirl15)
Sonia (Lonelygirl15)
Claire (Lonelygirl15)
Jack (WatchYourJack)
Charlie (KateModern)
Lauren P. (KateModern)
Sophie S. (KateModern)
Terrence (KateModern)
Jeremy (KateModern)
Meryl (KateModern)
Estelle (LG15: The Resistance)