Improvement: I would like to keep track of treatment plans sent to my patients

Originally submitted by the team at OCM:

We're thinking of having a way to lock treatment plans once they have been shared with a patient (emailed or downloaded). This will prevent patients claiming that they were quoted less or being charged too much.

If deciding to lock the treatment plan once it has been sent, we need to find out what usually changes:
- users shouldn't be able to change the price because this is the whole point of locking the treatment plan
- sometimes users need to change the provider if the dentist who quoted it isn't working there anymore or if they don't want to do the work anymore (what happens if the first provider offers a discount, but the second doesn't want to? Will sending another quote be the better option?)
- sometimes users might need to change the date (what happens if a dentist has given a time-based discount? "$200 off if completed before the end of the month". Won't changing the date change that quote?)

Should we be tracking anything else, or keeping anything else in mind? Thanks guys! Keen to get some ideas on this!