Is it possible to setup approval unit by specific accounts, entity and LoB?

The requirement is as follows:

• We are only submitting part of the expense accounts in the P&L hierarchy for approval
• Only specific entities and LoB are required for approval

e.g entity-A x LoB-A, entity-B x LoB-B

So I tried to setup approval groups in the application, and listed out the combination needs to be approved.

And I assigned the approval groups in the approval unit hierarchy.

After promoting the approval unit to the next level, I found that all accounts, and all LoBs are locked and not allowed for data input.

I thought only the specified data combinations listed in the approval groups will be locked after promotion.