How to handle mandatory fields in SAP Screen Personas

Hi Experts,

I have created a custom field on MK01 transaction and marked it as mandatory. This field belongs to the second screen of MK01(Name) and if I dont fill this field in the standard transaction error message will be displayed in the status bar.

If this mandatory custom field is not populated I want to display error message in the first screen of MK01.

Is there any way to do this?

One more thing, on pressing enter in this transaction it goes to the next screen can we overwrite this standard behavior and make it stay in the initial screen itself?

Regards,

Karthikeya