Can we create a commission tab in the Sales Order or Invoice records where all associated commissions will display?

Yes

I tried creating a saved search for commission because I'm just planning to have it displayed as a list view in my SO/Invoice subtab. However, I cannot seem to find the Sales Order or Invoice Number field from the result field in my search. Is there any other way I can display the commission tab?

Document number?

I tried Document Number, Source Transaction, Sales Order and Invoice Number but it yield no result. 😞

Applied To Transaction?