Bill,
You should be able to "resume all" and get the features back. It may get ugly...but in theory it should be possible.
Since you have internal datums you will need to deal with each feature's attributes individually and, most likely, in one big singular action. Save a "before" version to reference before you start your trek.
You stated you know what the datums need to be. That will be important as you move through the resolve.
Click"resume all" and when you are faced with a missing reference, click the "pause" icon and create it. Make sure you get the orientation and direction correct for the feature's sketch plane/reference. Uncheck the pause (resume feature), then replace the missing with the one you have just made. Rinse and repeat.
FYI....to all listening. Grouping features is generally a much discretion.
Dean