[Work in Progress Paper]
We address a particular kind of composition of access control schemes which include both a model to encode authorizations, and an administrative model to encode the manner in which such authorizations can change. The kind of composition we address is co-existence: two schemes working side-by-side in the same system in protection of the same set of resources with the same principals who seek access. We observe that practice appears to be ahead of research in this regard, and discuss case-studies we have carried out of three real-world compositions. We then articulate takeaways from the case-studies.