You must record in writing the transfer of knowledge undertaken by you and mention that you have done it successfully to the satisfaction of your office/superiors.
You must apply your rapport/goodwill and obtain a written communication from your reporting authority confirming the same.
Pls do not burden yourself much with the thoughts you are expressing. You may express your willingness to tender notice pay and ask to adjust in FNF statement and focus on your next venture.
If company becomes adventurous your lawyer shall be able to repel them successfully.