You can have an extension attribute built and tag devices with ur client
names. Add that column visible in Inventory display. Whenever you need
report you can just gather data of all devices and then filter it out
for your clients.
I would recommend integrating JAMF with your Asset Inventory tool and
then update the devices as 'Unmanaged' when status of that asset is no
more active on user name as per Asset Inventory Tool.
