To find user exit whever moving average price changed

Hi Experts,

I need to write my code whenever moving average price (MBEW-VERPR) get changed, few scenarios are:

- MBEW-VERPR can be updated from MR21 transaction

- Create Purchase Order then create delivery then transfer order, on confirmation of transfer order MBEW-VERPR can be changed

- It can be changed from MIGO transaction on Goods Receipt and Reversal.

-It can be changed from VL09 transaction on reversal of goods.

My requirement is to make my code as transaction independent, so I need to find out user exit( or enhancement spots) to write my code to update a z-table.

Can anyone help me to find out the correct place to write code?

Regards,

Piyush Yadav