How to add a partner to purchase order header?

Hi Gurus,

I created a custom partner function (901 - Dealer) and I want to add a partner with this function partner to header in purchase order (PO).

I'm using BBP_PO_APP_UPDATE_PO module function in BBP_DOC_SAVE_BADI badi adding new partner in IT_PARTNER table, but the new partner (with partner function 901) is not saved.

Why is not working this module function?

Is there another alternative to add a partner to PO header?

Thanks in advance and best regards,

Alonso Valenzuela