To answer your question, any changes in supervision arrangements must be approved by the NSRP and require the same consent forms. When there is co-supervision, typically supervisors may have some contact with each other throughout supervision, and are able to view the supervision reports of the other. You can provide your consent to them to speak, but NSRP does not feel that you would have to consent for them to be able to correspond, if the NSRP has approved them both as your supervisor.
Feel free to forward the required forms for Melissa McGonnell, along with her CV, and these will be added to the next NSRP Meeting agenda. Here is a link to the other consent forms:
https://www.ns-rp.ca/information-for-registrants/for-candidate-registrants/supervision-processforms/#Consent_FormsnWhen you submit your request it would be helpful for the NSRP to know why you are adding a second supervisor.
As for the title you may use, you may use “Dr.” but registrants would not be expected sign using both “Dr.” and “Ph.D.” at the same time. If you would like to sign as Dr. first name last name, followed by Psychologist (Candidate Register) that is fine with the NSRP, or you could use first name last name, Ph.D. followed by Psychologist (Candidate Register).
As to the question on signing off on reports, I have attached the FAQ which talks about this, which is up-to-date.
https://www.ns-rp.ca/information-for-registrants/for-candidate-registrants/faq/#cosigning_reports