The documents you will need to change your name on your certificate of competency depend on the category that your certificate comes under. The two different categories of certificates of competency are:
Low complexity certificates of competency are:
High complexity certificates of competency are:
Your replacement high complexity certificate will have the same expiry date as your lost, stolen or damaged certificate. If your certificate is due to expire soon, you should apply to renew it instead and include your change of name documents with your application.
Links
[1] https://www.amsa.gov.au/qualifications-training/equivalent-qualifications-and-skill-recognition/equivalent-first-aid
[2] https://www.amsa.gov.au/forms/certificate-competency-application
[3] https://www.amsa.gov.au/node/1527
[4] https://www.amsa.gov.au/forms/certificate-medical-fitness-international-certificates