Bottom Up Heuristic - SAP_PP_009 - object selection

[ez2]

We run bottom up heuristic and rescheduling in a Planning run to create a feasible plan taking component availabilities into account.

We have product A made of product B. Product A produced in resource A, product B produced in resource B.

In the Bottom up heuristic, when we select resource B as an object in the planning run, does the heuristic

a. shift the planned order B which is produced on resource B, looking at the component availabilities,

b. or does it shift the planned orders of product A?

Based on this example my next question is, should we

a. first run Bottom up heuristic for resource B, and then rescheduling for resource B,

b. or run rescheduling for resource B and then Bottom up heuristic for resource B?

I have done some tests and have an idea on the answers but I would like to confirm my thinking.

Thanks in advance.