Survey integrated with CRM doesn't add new responses, only updates

Our food company sends samples to customer to taste. I created a "Samples" module in CRM to keep track of these samples, linked to Deals and Accounts.

We also created an e-mail template to send from this Samples module, with an inserted Survey link.

Now, because we can send, say, a sample of oriental flavour and another sample of tropical flavour in one parcel shipment, we only send out one e-mail to accompany that shipment which holds only one survey link (the link in the mail template, linking to ${Samples.Sample ID}.

One parcel to ship = one record in the sample module, regardles of how many samples in that parcel.

We ask our customer to open the same link in that e-mail for each sample they taste and submit for each.

I expected that, for each submission, i would see a new line in the Zoho Survey related list, but it only updates. So I don't see one submission for oriental and another for tropical.

In the Zoho Survey/hub/integration, i did select "add record", which should cause a new record for every submission. Is this not the same as a new line in the related list?

What can I do to get a new line for each submission in each sample record?

Thanks for any input!