ISO 45001 integration with ISO 9001

(1) Can I incorporate the ISO 45001 into our ISO9001:2015 QM. I am not sure how to do so. Procedures I can handle using a separate volume.
Answer: You are correct, OHSAS 18001 is being replaced by ISO 45001:2018, and companies who have the previous standard in place need to transition before 2021 to keep a valid certification for their OHSMS. As for incorporating ISO 45001 into an ISO 9001:2015 management system, this is certainly possible and often preferred. Both standards now follow the same document structure so it is easy to see what is common, such as internal audit, control of documented information and management review. In this way you can even use the same processes and procedures for these common elements and ens ure that you cover both aspects of the processes.
You may find it helpful to read the free whitepaper: How to integrate ISO 45001 with ISO 9001 and ISO 14001, https://advisera.com/45001academy/blog/2018/09/12/how-to-integrate-iso-45001-with-iso-9001-and-iso-14001/

(2) - how would certification bodies audit us - in one go or separate occasions?
Answer: When a company has more than one certification it is possible to have one certification body perform the certification audits together, at the same time. There will be additional auditing time allotted, but like the internal audits it is possible to audit some elements together and cover both standards. However, this would only be the case if you have the same certification body for both standards, and if you chose to have different certification bodies for each standard, they may not be able to do a joint audit.
To better understand the requirements of ISO 45001:2018, see our whitepaper: Clause-by-clause explanation of ISO 45001:2018, https://info.advisera.com/45001academy/free-download/clause-by-clause-explanation-of-iso-45001