How I can save an array from a local variable into rule input?

Hi!

I'm trying to save values from a multiple dropdown into a rule input, but my code it's not working. I proved a!forEach in my submit button, but when i press the button only save the last item of my array.

a!localVariables(
    local!categoria: cast(
      'type!{urn:com:appian:types:FDC}FDC_CATEGORIA?list',
      rule!FDC_ER_getAllCategoria()),
      local!organismo:rule!FDC_ER_getOrganismoByCategoriaId(id: ri!categoria),
      local!guardarOrganismo:local!organismo,
      /*local!prueba:ri!cartaOrganismo.idOrganismo,*/
a!sectionLayout(
    label: "Section",
    contents: {
      a!sideBySideLayout(
        items: {
          a!sideBySideItem(
            item: a!dropdownField(
              label: "Categoría",
              labelPosition: "ABOVE",
              placeholder: "--- Select a Value ---",
              choiceLabels: local!categoria.coNombre,
              choiceValues: local!categoria.idCategoria,
              value:ri!categoria,
              saveInto:{
                ri!categoria
              },
              searchDisplay: "AUTO",
              validations: {}
            )
          ),
          a!sideBySideItem(
            item: a!multipleDropdownField(
              label: "Multiple Dropdown",
              labelPosition: "ABOVE",
              choiceLabels: local!organismo.coNombre,
              choiceValues: local!organismo,
              value: local!guardarOrganismo,
              saveInto:local!guardarOrganismo,
              searchDisplay: "AUTO",
              validations: {}
            )
            
          ),
          a!sideBySideItem(
            item: a!buttonArrayLayout(
              buttons: {
                a!buttonWidget(
                  label: "SAVE",
                  saveInto:a!forEach(
                    local!guardarOrganismo,
                    a!save(ri!cartaOrganismo.idOrganismo,fv!item.idOrganismo)
                  ),
                  style: "NORMAL"
                )
              },
              align: "START"
            )
          )
        }
      )
    }
  )
)

I hope you can help me. Thanks!