Thunderbird has 2 default address books. The Personal and the Collected. I suggest that you move the contacts from your imported books into the personal book.

Open the address book window. Make sure the Directory Pane is showing on the left margin.

If not, select View-Layout-Directory Pane

Click on the folder for one of the imported books so it displays in the main window. Select the contact or contacts that you want to move. Drag the selected contacts to the folder of the new book and drop them there to move them. Control+a will select all Holding the control key while clicking contacts will select anything you click on. Clicking one item and then moving to another item and holding the shift key while clicking the second item select the 2 items clicked on and all items in between.

OK up to point of "drag the selected to the folder...". After selecting the entire book's contents, I click and try to drag, but get the "circle with a line through it" icon that won't let me more to the address book I want.

Can you drag a smaller amount of contacts? How about just one?

I just reread the original post. I think it might be the lists stopping you. In order for a list to exist in an address book the contacts on the list must exist in that book. My guess would be that since the contacts do not exist in the book yet it will not allow the move with the lists included. You could try doing a copy instead of a move and see if that works. Hold the control key down while dragging and dropping. You will see a plus sign appear to indicate a copy.

If that works you can go back, after making sure all lists and contacts moved, and delete the original book.