Programmatically set FIFU image to product

Ciao, first and foremost, 1000 thanks for great plugin, works really really well!

Since all the products in my webshop are created programmatically from an external feed (i.e. there is zero manual creation from WP admin backend), I am trying to include support for the FIFU image within the external creation process (PHP code). Based on some DB analysis, I thought all I needed to do was:

1. add the postmeta ‘fifu_image_url’ to the product
2. create the post entry with type ‘attachment’ for the FIFU image, together with the 3 postmeta ‘_wp_attached_file’, ‘_wp_attachment_image_alt’ and ‘_wp_attachment_metadata’

But still the FIFU image is somehow not correctly set, since I need to go to the WP admin, and manually click update in the product edit page to see the FIFU image set up completed, and the image properly shown in the front-end.

Would it be terribly annoying to ask you what am I missing? I tried to monitor any DB changes happening after I click update, but I cannot see anything related. Is there a list of FIFU images somewhere in the DB that I need to update?.

Thanks in advance for your help

M