Scenarios are designed to let some objects be different from a baseline situation, whilst other objects remain the same as in the baseline situation.
Suppose you create a base scenario with many road segments, barriers and houses in it.
You want to test the effect of re-aligning a road segment. So you load the base scenario, change the alignment of a road segment and then save it as a new 'child' scenario, and call this 'New Road'.
Now you realise that you entered all the roads as 5 m wide, but they should have been 7 m wide, so you load the New Road scenario, select all roads and change the width to 7 m and commit this change to the presently-loaded 'New Road' scenario.
If you now reload the base scenario, you will find that all the roads are still the original 5 m wide. What is more, if you make any other changes to the road (eg the surface texture) these do not get through to the 'New Road' child scenario.
This is because when any object is changed in the child, those changes do not affect the parent BECAUSE inheritance from the parent is disconnected when you make the change in the child.
If on the other hand, you had loaded the parent scenario and had changed all the road widths in the parent, then the new road widths would appear in the child, except for the road that you realigned in the child. When you re-aligned it in the child, this broke any further inheritance from the parent.
There is no method of restoring the inheritance once it is broken, so you need to take care when making changes - be careful NOT to make changes in a child unless it is OK for inheritance to be broken.
You can easily tell the scenario from which any object is getting its properties. If you open its Object Properties screen, a few lines from the top is a line called 'Root Scenario'. This has the name of the scenario from which that object gets its properties. This might be the base scenario, or one of the child scenarios.
