Thanks for your quick reply, it is highly appreciated, but that is only the sock for the T-shirts and not for the designs if I am not mistaken? I was wondering if it is possible to add stock numbers to the designs as marked in red in the image I added in the attachment.
This feature is not supported yet. You could head on over to the feature request forum and have a look at the discussions there or add a new topic with a request for the feature you are looking for so we can keep it in mind for further updates.
Thanks for the tip!!