Upload xls file linked to pernr in background

Hello,

I need to know the best practice (and the easiest) to upload an excel file into the attached files part from the PA transactions (PA30/20).

In my program, I manage other files (.pdf, .doc..) with FM GUI_UPLOAD and SBCOMS_SR_FROM_DOCUMENT_CREATE.

I don't know the number of columns so It's not possible to use FM like TEXT_CONVERT_XLS_TO_SAP or ALSM_EXCEL_TO_INTERNAL_TABLE.

I wonder if is it mandatory to convert the contain of the excel file into an internal table to upload it into PA transaction.

Do you have simple solution ?

Thanks in advance.

David