RE: Change of controlling area
there is no standard scenario within SAP LT to achieve a company code transfer to another controlling area.
I assume the source controlling area contains more than one company code and some of the company codes should stay there. The challenge in this scenario is to find valid split/selection criteria to select the data that needs to be transferred from the source controlling area to the target. The company code will not be sufficient in all cases. This is more than just a technical exercise because it depends on your specific CO setup. Feel free to contact me if you need more help on that.