Integrating ISO 14001 & ISO 45001 into ISO 9001

Answer:
As you have indicated, many of the processes are similar between the three standards, such as internal audit and management review, so creating an integrated management system does not add three times the work. The main processes to add onto the ISO 9001:2015 QMS would be:
For ISO 14001:2015 EMS, environmental aspect and impact assessment (how the company interacts and affects the environment), determining environmental legal requirements and compliance and preparation for emergency response.
For ISO 45001:2018 OHSMS, consultation and participation of workers, hazard identification and assessment, OH&S determining legal requirements and compliance, elimination of hazards, preparation for emergency response and the addition of incident investigation into the corrective action process.

For a better understanding of how to integrate these standards, see the whitepaper: How to integr ate ISO 9001, ISO 14001 and ISO 45001, https://info.advisera.com/9001academy/free-download/how-to-integrate-iso-9001-iso-14001-and-iso-45001