Your contracts of employment should have a clause to allow you to make reasonable changes, if you don't, you should do this now.
We often find that employees will not agree to carry out additional tasks because they have not done so before and they consider these to be a change of their terms, even when these are minor things. This is not always their fault because changes in practice often set in over time and they might have simply got used to that regime.
The new registration regime makes it essential for you to train up staff and be able to prove that they are trained and putting into practice what you taught them.
As an example, if members of staff do not meet confidentiality requirements or refuse to be trained, you cannot allow them to access patient records nor perform patient facing tasks. In essence, they will no longer be able to perform their duties, potentially face disciplinary action or even dismissal.
Of course it is not good practice nor good business sense to jump straight into "dismissal mode" and you will find that most staff can be easily persuaded that this is now necessary and will cooperate in the spirit of teamwork. Good management works on the old adage "Never ask as a right what you can get as a favour".