The issue as a bug, VSTS#215030 - "No option to create child or peer assets from Asset Hierarchy right-click when integrated". This bug will be reviewed by the Product Manager for repair in a future release of APM.The workaround is to use the "Create Multiple Child Assets" option from the right-click menu or to open the logical parent asset and use the Asset pulldown menu's Create New option.
To change the Parent Asset of a non-integrated asset, open the Asset and change the parent asset manually from the Asset's Properties view General tab Location page.