Move main domain to become add-on domain on other account

I'm trying to clean up our server after years and years of sprawling neglect. Too many of our test/play domains have been set up as full accounts and need to be consolidated. Example: testdomainone.com - Account: testone playdomaintwo.com - Account: playtwo devdomain.org - Account: devorg The goal is to move "testdomainone.com" and "playdomaintwo.com" to become add-on domains under the "devorg" account, removing the "testone" and "playtwo" accounts. Is there a way to make that work, or is it a manual process of copy files, copy DBs, copy DNS, remove accounts, then add domains? (yuck) Thanks!