So ideally, before upgrade save the Beech's: Baron 58 and the King Air) (and/or any default planes that you may have custom liveries set up within the P3D directory), then upgrade the content to 4.4.
Now if you wanted the Beech's after the upgrade: can do that by pulling out the 4.4 content, 4.3 content back in, pull the beech's out and saving them elsewhere: (Simobjects plus any gauges/effects), then redo the content to 4.4. (But you can't get the custom liveries back for default aircraft with unless you have saved them prior or have an alternative copy/backup to restore them). (IE: Baron 58 with RTMM livery)
Later an user can place the saved beech's back into the sim or to an alternate addons folder/drive.
Norm