Hi Harris,
No need to change PA0002 - that's all fine.
From your screenshot it seems the middle name field is not meant to be used for Molga 40 with screen 2040. So, if this really is the standard screen for Molga 40, your options are:
1) you could use a different screen, but then you are likely to lose some special features required for your country
2) you could add a custom field with the infotype enhancement feature in transaction PM01. If you have at least a junior developer he/she can follow the documentation to do that easily. In that case, I would recommend to change the automatically created "additional field" screen and refer the custom field on the screen to the standard field on PA0002.
3) However, even though enhancing standard infotypes with PM01 is a standard procedure this might still collide with some standard SAP features for Molga 40. standard reports sending data to the government will not read your new field. They probably expect the middle name in one field together with the last name. So, you'd have to check, whether moving the middle name into a separate field works for standard statutory reporting first, before you take any of these actions.
Kind regards
Sven