Hi. If you add or update notes, do they see the changes? If so, then they have a link to your account, and if you 'change' a note by deleting it, they'll see that (or not) too! There are a few options...
Tell your colleagues to copy all the notebooks to their own account(s). Each one will then have their own copy of the content. NB If one user makes a change to a note, no-one else will see the change. They all have individual copies.
Get one colleague to 'host' the notebo
OK - so one of your colleagues needs to mirror the structure of the notebooks which you have shared by creating a series of copy (empty) notebooks with the same names as your originals in their Evernote account. Then, they copy all the notes which you have shared from your notebook "<shared1>" into their copy notebook 'shared1'. They now 'own' a snapshot of your notebook. They can share that new notebook with their colleagues exactly as you have done, and your colleagues will see two