Purely for the sake of my own academic fun, as well as to directly attempt a reply to the OP's question regarding his 9904 movement, I will posit a thesis. I am thoroughly a technical novice when it comes to watches. Ergo, I will let you guys tear me apart with ridicule for my naiveté or find some merit.
Preface Definition (very general): To use the term in house, most or all vital parts of a watch's mechanics must be developed, constructed, and produced by said manufacturer.
Thesis: The 9904 is based upon the 9300 movement. The 9300 takes George Daniel's coaxial escapement and combines it with twin barrels, silicon hairspring, column wheel, and vertical clutch. While the escapement was not invented by an employee of Omega, they purchased this technology and own it outright. Thus, it's built and utilized solely by Omega and falls under in house. Their twin barrel system is unique in that it was developed and is utilized more so for continuity of accuracy through its power reserve vs most multi barrel systems which are in place purely for prolonged reserve. Column wheel and vertical clutch systems are not unique to Omega but Omega does assemble their own during watch construction in house. Nivarox is owned by Swatch group and makes the silicon hairsprings used in Omega watches. Omega has constructed their new manufacturing, movements, and construction to comply with METAS certification (utilizing the 9300 backbone in this specific instance).
Conclusion: Based upon the above information, the 9904 movement can be considered as being "In House" by Omega. Unless one desires to practice a reductio ad absurdum argument.
Okay, that's my novice attempt at a stance for the 9904 to be considered falling under general "in house" guidelines by the varied reasonable working definitions. I will now prepare myself for the inevitable verbal flogging for missing some vital piece of information which turns my thesis into a collapsing house of cards...
Post Script: I sometimes ponder over if I were to spend this much time on paperwork vs watch forums. I'm thinking I would need go into work on the weekend to catch up on patient charting far less frequently. However, this is a lot more fun!
