I have a roster type form that requires multiple signatures

I have a visit log that requires my clients to initial it indicating I was there, this can be several clients per day, I send file at the end of the day to my supervisor. After the first visit, I have the client initial it, I save and close the file, next visit I open the file but it is locked from editing for the next person, once a signature is saved, the log can no longer be edited. This is not an official document, I do not need that tight of security, any help is appreciated.