Appending a query

I have some multi selects which I want to function using grouping. I’m using slimselect

The data structure is this:

 // Mix - option and group options
  data: [
    {text: 'Human'}, // regular option
      label: 'Animals',
      options: [
        {text: 'Cat'},
        {text: 'Dog'},
        {text: 'Bird'}

All is working fine so far, I can return the data from a repeat in server connect in the correct format:

"listResources":[{"label":"Equipment123","id":"0a748ef7-734a-421c-aae7-6492bdd636ef","options":[{"text":"Room 1","value":"43775c46-9449-4d14-9654-c3802baf6fc6"}]},{"label":"Rooms 123","id":"7592726b-1f7a-4cfc-91c0-6293d3f8af56","options":[{"text":"Laptop","value":"2f6fd72e-45db-4105-ac45-ade2715f28c1"},{"text":"Resource4","value":"93a41a0a-ce15-46ba-919e-e0e03cf6ff45"},{"text":"Projector","value":"bc739c4c-99bf-4071-995e-ea206cab8050"}]},{"label":"Vehicles","id":"d098210d-62b6-4ee6-8d86-393b246f93cf","options":[]}]

I’d like to append a second query with a manually entered label of ‘Unallocated’. So these options:

"queryUnallocated":[{"resource_name":"Room 2","id":"8c4a74ae-6e37-4391-b7"}]

to appear within the first results set with a label of Unallocated. The options from queryUnallocated have an empty field, those under listResources have a label ID which links to the repeat fields.

This is the server action:

I’ve tried a few routes, adding a set value step to create a new label and using a data transformation to join it to the labels query. Using set value to create the label and options array, then joining this to the listResources repeat. I’m not sure that you can run a join off a set value step.

I’m sure there must be a simple solution but I’m struggling to find it! Anyone have any suggestions?