How do I increment a structureItem ID # in a blueprint query?

Hi. I have a website page (‘testimonials’) with a list of customer quotations in a structure field. Naturally, the structureItem IDs start with #1 in the panel table…

I then want the client to be able to choose which quotations are shown on the homepage, so I’ve added a multiselect field in the homepage blueprint that queries the list of quotations on the testimonials page. I’m including the item ID in the displayed multiselect tag but it defaults to start at #0

Is there a way to add a ‘calculation’ in the query, to increase each structureItem ID by 1 to match what’s displayed in the structure table? Current blueprint setup as follows…

  label: Selected testimonials
  type: multiselect
  options: query
    fetch: site.find("testimonials").testimonials.toStructure
    text: "{{ structureItem.customer }} from {{ structureItem.hometown }} (#{{ }})"
    value: "{{ structureItem.customer }} from {{ structureItem.hometown }}"

Many thanks.