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I somehow undid a check out and continued to make changes to my model. During that time, a coworker checked it out and made changes. Is there a way to incorporate my changes without overwriting his?
Running Creo 3.0 and Windchill
23 years using Pro/E... rookie mistake.
You could try running the trail file recorded on your machine (changes you made) on the other user's latest model, but trail files can be quite finicky so differences in orientations may affect picks and so on... I'd be most concerned about differences in references between the two models.
If it were me, I'd be more confident in redoing my work manually. I find it's always quicker when you know what the end game is and is often as fast or faster than messing around with "recovery" techniques.