I have requirement in VISTEX memberships to update custom fields in /IRM/GMLMBR table

I have requirement in VISTEX memberships to update custom fields in /IRM/GMLMBR table.

There are two options on my research

1) Using Function module /IRM/GML_CHANGE which is not working to update the custom z fields added.

2) SHDB BDC Recording the /IRM/GMLM transaction and updating the fields from the excel which is also not working as I has the ALV to enter memberships fields.

Please suggest any alternative or let me know any solution from above two solutions.