For those that missed it, a Joint Cyber Security Advisory was issued on the 11th May 2022, with a number of recommendations for managing the risk within the MSP supply chain. They're all useful reminders and references and may add weight to any recommendations that you may be putting forward.
https://www.cisa.gov/uscert/sites/default/files/publications/AA22-131A_Protecting_Against_Cyber_Thre...