Can we use HCM-only BUs and Separate BUs for Finance and Procurement in a single Oracle environment?

Summary:

We are already live on Oracle HCM with BUs defined a a particular way. We are now looking to implement Finance and Procurement in the same environment. Our SI is proposing a new list of BUs for Finance/Procurement. HCM will continue to use their existing BUs. Finance and Procurement will implement new BUs as per geography (Countries). We are trying to find out if this will add any risk on certain functionalities not working due to this e.g., requisitions. Has anyone used separate BUs between HCM and Finance/Projects? If yes, please share your lessons learned to see if this