Can't move email address contact information into sub-folder.

Question

I created a "top level" address folder named "Personal Address Book". Under that top level, I created a sub-folder named "Family". I entered the name, email address, and work telephone information for my son. That data was then copied (not moved) to the sub-folder named "Family."
I then entered his wife's name and telephone number (don't have her email address data) into the "Personal Address Book" I am unable to get that data copied to the "Family" sub-folder.
What is going wrong?
A user should have the ability to either MOVE or COPY the information from the top level folder to only one, or more than one, sub-folders. This would allow the user to have a relatively short list in the top level folder, and the information organized in the sub-folders without duplication.

Answer 1

Let's back up a bit. A Mailing List is not a subfolder, despite its appearance. You can't MOVE a Contact into a Mailing List, but you can COPY a Contact into a Mailing List. So any Contact in a Mailing List must exist in the parent address book.
If you don't habitually send a message to multiple recipients then you haven't any need for Mailing Lists.
OTOH you have suggested that in fact you may wish to send the same message to various government officers, in which case a Mailing List may be useful. You can of course create multiple mailing addresses; so if you write to A, B and C on tax matters, you can create a Mailing List named Tax constining A, B and C. If you write to B, C and D on defense matters, then you create a Mailing List named Defense containing B, C and D. If you frequently want to bombard everyone indiscrminately with the same message, then create another Mailing List called All and containing A, B, C D and all the way up to Z. Mailing Lists are subsets. The can intersect, as we see in a Venn diagram.
Personal Address Book and Collected Addresses are hard-coded into Thunderbird. If you delete the underlying data files they will simply be re-created the next time you run Thunderbird.
You can, as gnospen said, disable or modify the collection of addresses. You can arrange for such collection to go to another address book of your choice, or disable it altogether. I'd advise against writing them into a "working" address book, simply because it will become polluted by what you perceive to be random addresses. Leave it set to write to Collected Addresses and you know that the random addresses are contained.
You can rename both Personal Address Book and Collected Addresses via the Config Editor, though I have never understood the motivation to do so.
How do you, internally, go about organizing or choosing whom to address a message? Some users seem to be visual and like to pick from a list and ask how to see their address book when composing their message. To them I point out the Contacts Sidebar. In the Write window, press F9 to see a small address book at the left. You can select Contacts from this to add to your message.
For myself, I mentally visualise the intended recipient, and then start typing his name or address straight into the addressing box. Thunderbird will quickly start offering contacts form my address books which match what I've typed.
In this second case, it doesn't matter which address book any contact is stored in, since it will be found wherever it is. So I may as well just put all of my contacts into Personal Address Book, since no further organization or subdivision is actually needed.
If you feel a need to organize your contacts, then create new address books as required. When using the contacts sidebar, it shows only one address book at a time, so for the visual types amongst us, it winnows down the displayed addresses to the selected address book. Create a "Government" address book, select it, and the Contacts Sidebar will show only your legislative correspondents.