I did not read all the responses... first.. get a lawyer, fast!
By your descriptions, I'm not sure the 2 companies don't play in some of the same areas. As for company lists... you don't need a written list to be in the wrong. It is too easy to remember who you've used before without thinking about it.
Get a lawyer familiar with this part of the law
Figure out if DD signed something with the new employer that says she has no remembrances... like this agreement. This is what they are looking for. She could be in trouble with them. It is best to work these out when you get a new job, not after. You can put them at risk... which will put her more at risk potentially.
I hate to say this... use this as a learning experience with DD... know what you sign. I had these where my previous company
owned all the inventions and improvements for 1 year following my employment if they related to anything the company was working on. talking mega company here.
Didn't matter if I had worked on it at the previous company... or that I got laid off (facility closure)
The other thing to note, all things in these agreements may not be enforceable. Get a lawyer.
I have seen companies not hire people until these agreements were worked out.
All my employers had these agreements. Some narrowed the context of them to a somewhat limited area. But most would prevent you from going to someone they saw as a competitor.