How MIGO/MIRO updates SRM PO with GR/IR number?

Hi Experts,

For a ECS SRM PO, if we do MIGO/MIRO directly in ECC, which FM updates the PO history in SRM with ECC GR/IR number immediately? Since CLEANER or GET STATUS jobs run at intervals, I guess these jobs do not do it.

So I would like to know the call stack of FMs. What is the FM that is called by MIGO/MIRO transaction till the FM that updates PO's RELATED DOCs section with ECC GR/IR number?

Thanks!

Regards,

Karthik