Merge Form Data and Form Archive for multi-instance action

The workflow consists of 3 steps:-
Step 1: 1 action, doing Section A
Step 2: 10 or more actions, doing Section B
Step 3: 1 action, doing Section C

I found out that COPYDATA and MERGEFORM is use to combine multiple Form Data/Form Archive with different section into one but it do not solve my problem.

My problem:
In Step 2, there may be 15 actions for 15 users to do the approval at a same time for the own Section B.
After all users do the approval in Step 2, the action will pass to Step 3.
In Step 3, the user should be able to see all the approvals(Section B) done by 15 different users in the Form Archive.

Is there any methods to solve the problem above?