Attached picture is from DS training material and illustrates for MBOM Revise

(Collaborate using Data Management from Design through Process Engineering)

I think the general EBOM and MBOM work process is as follows. .
1. Designer revises EBOM.
2. Manufacturing Engineer verifies the changed EBOM and then revises MBOM.

So I think EBOM and MBOM should be revised separately.

However, the Training manual explains that EBOM and MBOM should be revised at the same time for automatic update.

Q1) Do I have to revise EBOM and MBOM at the same time?

Q2) I also want to ask if there is a way to revise EBOM and MBOM separately.

Please help me.