You can simply drag and drop contacts between Address Books.

Sorry but I don't know how to have multiple address books open at the same time!

Open your address book window.

If the Directory Pane is not showing, turn it on.

View-Layout-Directory Pane

Click on the address book folder that you are going to move contacts FROM.

Select the contacts that you are going to move. Drag them to the folder of the new address book and drop them there. Selecting one contact and the pressing control+a will select them all.

The Personal and the Collected address books are Thunderbird defaults and cannot be deleted.

When I click on VIEW, I do not get the Layout-Directory Pane option. Sorry again!

Then you do not have the Address Book window open.

HELP PLEASE! I clicked on something and now all my Thunderbird address books have disappeared. They formerly were in a pane on the left when I clicked to send a message. PLEASE!!

Press F9 to turn on the Contact Sidebar in a Write window.

Thank you! Thank you! Thank you!

Now I'm back to my original issue but it seems so minor now, I'll forget about consolidating them!

It sounds to me like you have never clicked on the address book icon on the main toolbar... you have been trying to apply address book information to the contacts pane in the compose window quite unsuccessfully .