How do I fulfill all the clients’ requirements? | SAP PM Interview Questions

You could create equipment with reference to another (say dummy master equipment).
Then utilize user-exit IEQM0003 (Additional checks before equipment update) to pop-up your warning message.
You could further investigate the following:
Use IEQM0003 to kick-off a batch program or workflow to re-enter the equipment (after initial save) and add data.
Create new event/method for business object EQUI (TCode SWO1).