Is it possible to achieve multiple selection in cascading dropdowns

Did you consider to apply that "pass to next" logic inside the saveinto of the first dropdown?

Sample code for reference

a!localVariables(
  /* Sample hierarchical data: Adjust to your data source */
  local!lv1Labels: {"Cat1", "Cat2", "Cat3"},
  local!lv1Values: {1, 2, 3},
  local!lv2Labels: {"1-A", "1-B", "2-A", "2-B", "3-A", "3-B"},
  local!lv2Values: {11,12,21,22,31,32},
  local!lv3Labels: {"11-i","11-ii","12-i","21-i","22-i","31-i"},
  local!lv3Values: {111,112,121,211,221,311},
  local!lv4Labels: {"111-a","111-b","121-a","211-a","311-a"},
  local!lv4Values: {1111,1112,1211,2111,3111},
  local!lv5Labels: {"1111-x","1111-y","1211-x","2111-x"},
  local!lv5Values: {11111,11112,12111,21111},

  local!selected1: {}, local!selected2: {}, local!selected3: {},
  local!selected4: {}, local!selected5: {},
  local!tmp2Labels: {}, local!tmp2Values: {},
  local!tmp3Labels: {}, local!tmp3Values: {},
  local!tmp4Labels: {}, local!tmp4Values: {},
  local!tmp5Labels: {}, local!tmp5Values: {},
{
  /* Level 1 */
  a!multipleDropdownField(
    label: "Level 1",
    choiceLabels: local!lv1Labels, choiceValues: local!lv1Values,
    value: local!selected1,
    saveInto: {
      local!selected1,
      /* Clear children */
      a!save(local!selected2, {}), a!save(local!selected3, {}), a!save(local!selected4, {}), a!save(local!selected5, {}),
      /* Filter L2 */
      a!save(local!tmp2Labels, index(local!lv2Labels, wherecontains(local!selected1, local!lv1Values), {})),
      a!save(local!tmp2Values, index(local!lv2Values, wherecontains(local!selected1, local!lv1Values), {}))
    }
  ),

  /* Level 2 */
  a!multipleDropdownField(
    label: "Level 2",
    choiceLabels: if(length(local!tmp2Labels)>0, local!tmp2Labels, local!lv2Labels),
    choiceValues: if(length(local!tmp2Values)>0, local!tmp2Values, local!lv2Values),
    value: local!selected2,
    saveInto: {
      local!selected2,
      /* Clear children */
      a!save(local!selected3, {}), a!save(local!selected4, {}), a!save(local!selected5, {}),
      /* Filter L3 based on L2 */
      a!save(local!tmp3Labels, index(local!lv3Labels, wherecontains(local!selected2, local!lv2Values), {})),
      a!save(local!tmp3Values, index(local!lv3Values, wherecontains(local!selected2, local!lv2Values), {}))
    }
  ),

  /* Level 3 */
  a!multipleDropdownField(
    label: "Level 3",
    choiceLabels: if(length(local!tmp3Labels)>0, local!tmp3Labels, local!lv3Labels),
    choiceValues: if(length(local!tmp3Values)>0, local!tmp3Values, local!lv3Values),
    value: local!selected3,
    saveInto: {
      local!selected3,
      a!save(local!selected4, {}), a!save(local!selected5, {}),
      a!save(local!tmp4Labels, index(local!lv4Labels, wherecontains(local!selected3, local!lv3Values), {})),
      a!save(local!tmp4Values, index(local!lv4Values, wherecontains(local!selected3, local!lv3Values), {}))
    }
  ),

  /* Level 4 */
  a!multipleDropdownField(
    label: "Level 4",
    choiceLabels: if(length(local!tmp4Labels)>0, local!tmp4Labels, local!lv4Labels),
    choiceValues: if(length(local!tmp4Values)>0, local!tmp4Values, local!lv4Values),
    value: local!selected4,
    saveInto: {
      local!selected4,
      a!save(local!selected5, {}),
      a!save(local!tmp5Labels, index(local!lv5Labels, wherecontains(local!selected4, local!lv4Values), {})),
      a!save(local!tmp5Values, index(local!lv5Values, wherecontains(local!selected4, local!lv4Values), {}))
    }
  ),

  /* Level 5 */
  a!multipleDropdownField(
    label: "Level 5",
    choiceLabels: if(length(local!tmp5Labels)>0, local!tmp5Labels, local!lv5Labels),
    choiceValues: if(length(local!tmp5Values)>0, local!tmp5Values, local!lv5Values),
    value: local!selected5,
    saveInto: local!selected5
  ),

  /* Debug: Selected values */
  a!textField(
    value: local!selected1 & "|" & local!selected2 & "|" & local!selected3 & "|" & local!selected4 & "|" & local!selected5,
    label: "Selected: ",
    readOnly: true
    )
}

)

Hi [mention:d3f7da62bd4c4db4bc3402f1a67e7747:e9ed411860ed4f2ba0265705b8793d05] ,

Here is an example of multiple selection using cascading dropdowns.

a!localVariables(
  local!countries: { "India", "USA" },
  local!statesByCountry: {
    "India": { "Rajasthan", "Maharashtra" },
    "USA": { "California", "Texas" }
  },
  local!citiesByState: {
    "Rajasthan": { "Jaipur", "Udaipur" },
    "Maharashtra": { "Mumbai", "Pune" },
    "California": { "Los Angeles", "San Francisco" },
    "Texas": { "Houston", "Dallas" }
  },
  local!areasByCity: {
    "Jaipur": {
      "Malviya Nagar",
      "Vaishali Nagar",
      "Mansarovar"
    },
    "Udaipur": {
      "Hiran Magri",
      "Fatehpura",
      "Shobhagpura"
    },
    "Mumbai": { "Andheri", "Bandra", "Dadar" },
    "Pune": { "Wakad", "Hinjewadi", "Kothrud" },
    "Los Angeles": { "Hollywood", "Venice", "Beverly Hills" },
    "San Francisco": { "Mission District", "SoMa", "Sunset" },
    "Houston": { "Downtown", "Midtown", "Uptown" },
    "Dallas": { "Deep Ellum", "Bishop Arts", "Lakewood" }
  },
  local!selectedCountry,
  local!selectedState,
  local!selectedCities,
  local!selectedArea,
  local!showSelectedChoiceforState: touniformstring(
    a!forEach(
      items: local!selectedCountry,
      expression: index(local!statesByCountry, fv!item, {})
    )
  ),
  local!showSelectedChoiceforCity: touniformstring(
    a!forEach(
      items: local!selectedState,
      expression: index(local!citiesByState, fv!item, {})
    )
  ),
  local!showSelectedChoiceforArea: touniformstring(
    a!forEach(
      items: local!selectedCities,
      expression: index(local!areasByCity, fv!item, {})
    )
  ),
  {
    a!multipleDropdownField(
      label: "Country",
      choiceLabels: local!countries,
      choiceValues: local!countries,
      value: local!selectedCountry,
      saveInto: {
        local!selectedCountry,
        a!save(
          {
            local!selectedArea,
            local!selectedCities,
            local!selectedState
          },
          null
        )
      }
    ),
    a!multipleDropdownField(
      label: "State",
      choiceLabels: local!showSelectedChoiceforState,
      choiceValues: local!showSelectedChoiceforState,
      value: local!selectedState,
      saveInto: {
        local!selectedState,
        a!save(
          {
            local!selectedArea,
            local!selectedCities
          },
          null
        )
      }
    ),
    a!multipleDropdownField(
      label: "City",
      choiceLabels: local!showSelectedChoiceforCity,
      choiceValues: local!showSelectedChoiceforCity,
      value: local!selectedCities,
      saveInto: {
        local!selectedCities,
        a!save(local!selectedArea, null)
      }
    ),
    a!multipleDropdownField(
      label: "Area",
      choiceLabels: local!showSelectedChoiceforArea,
      choiceValues: local!showSelectedChoiceforArea,
      value: local!selectedArea,
      saveInto: { local!selectedArea }
    )
  }
)