Change field for an invoicedocument item (MM)

Hello,

Is there a way (function module for instance) to change an item, in particular to change the field SGTXT (field DRSEG-SGTXT) of an invoicedocument made in MM (transaction MIRO or MIR7).

For the specific group who will want to change this field, it is not advisable to give them transaction MIR4 to change the document-item.

Any help is welcome.

Bert