I am getting no help with extending marketpress product fields

Dear support,

I have posted this question in the forum:
https://premium.wpmudev.org/forums/topic/how-to-extend-product-fields-and-filter-them#post-486204

But nobody seems to reply.

So I wonder if someone from the staff could have a look at my question and give me some advise.

I'm a PHP developer but I need some orientation on how to do this.

Thanks a lot!
Rama