Hey i have a many2many field in which i want to append the ids of all my lines in the wizard on clicking create vendor bill button but when i append it and pass value to the field i get only one out of my 2 ids as it is overwriting, here is my code

for rec in self.shipment_service:
    print(rec)
    service_val = {
        rec.service_id.id
    }
    service.append((6,0,service_val))

invoice_vals = {
       'service_id': (4,service)
}

whatever it try doesnt seem to work and it keep on overwriting