[Freeipa-users] Converting an outside CA to a subordinate CA under IPA's Root CA

We had a developer team deploy their own CA and then issue a slew of certificates for users' workstations and other servers, and now they want us to deploy those certificates more widely. I'd rather find a way to bring their CA under ours so that the root CA certificate we already distribute will make theirs "just work" rather than having to distribute another set of root CA certificates. Is this possible, or would they have to start over and build a subordinate CA from the ground up to make it work? If it's perhaps possible, under what circumstances? Thanks! Bret