Re-assignment of wrongly edited items

Dear Community,

I was told to update an item which is part of a curriculum.

- The item consists of two objects (practical part & e-learning)
- The objects are supposed to be separated, I wanted to create a second item instead so we can add additional languages

- The curriculum which the item is part of has an assignment profile which is active since last year
- New assignments should include the new version of the old item and the new item

The problem is, when I first started on this task I had no idea how complex it was going to be and that I would have to revise the item and the curriculum, and thought it would be sufficient to simply change the item.

I clicked on "add object" to the item, and was asked to re-assign it after I click on okay. On the next page I was not able to select users for re-assignment (for unknown reasons?), so I closed the tab and thought the changes hadn't been saved.

However, it looks like the changes actually WERE saved and some users now see the new version that I was going to revise eventually. I can only see who has been assigned this item in the past week since we have made changes, which is about 50 users.

I would like those to be re-assigned to the old model but can't see how far they have worked already on the individual objects.

This is super frustrating, I am completely lost and don't know how to fix any of this.

1. How to fix the assignment for those who saw a "wrong" version without knowing the object completion status
2. How to revise the item and the curriculum and have both assigned only for new users.

If someone can help I'll be over the moon. I am happy to answer more questions if the problem isn't clear.