I forgot to say that it's going to be in the 50,000+ CIs. We have around 80,000 employess, 2-3,000 power related devices, and about 100+ locations. So creating them and updating them manually is not really an option. I'm not sure if we are licensed for MAM.
look the best option is to upgrade to BAC 7, then create CIT called personal and via the method I explained populate the CMDB with CIs, later via enrichment you can associate the CIs to be personal CIT.
You can later do it for all CIs you mentioed even 50000 CIs.