Can we insert multiple dropdown within another multiple dropdown.

Short answer: no.

I'm not quite sure what you even want - but I'm guessing you're after something that we'd usually do via what we call "cascading dropdowns".  What exactly is your use case / requirement?  You haven't provided much detail here for us to go on..

a!sideBySideItem(
                          item: a!multipleDropdownField_20r2(
                            label: "Therapeutic Area",
                            labelPosition: "ABOVE",
                            placeholder: "---Select all that Apply---",
                            choiceLabels: index(local!therapeuticArea.data, "name", {}),
                            choiceValues: index(
                              local!therapeuticArea.data,
                              "therapeuticAreaId",
                              {}
                            ),
                            value: if(
                              rule!APN_isBlank(ri!therapeuticAreaIds),
                              null,
                              ri!therapeuticAreaIds
                            ),
                            saveInto: {
                              ri!therapeuticAreaIds,
                              a!save(ri!primaryProductIds, null),
                              a!save(ri!studyRequest.otherProduct, null)
                            },
                            required: true,
                            disabled: and(
                              ri!studyRequest.externalStudyStatus <> cons!ISR_TEXT_STATUS_APP_PI_DRAFT,
                              not(
                                rule!APN_isBlank(ri!studyRequest.externalStudyStatus)
                              )
                            ),
                            validations: {}
                          )
                        ),

In the above code if we select any one value from the "index(local!therapeuticArea.data,"name",{})" .For example if we choose "cat" from the choice values then again another multifield dropdown values should visible when we choose on the "cat" in the same multidropdown field.

let me know is there any solution for it

sireesha said:

if we choose "cat" from the choice values then again another multifield dropdown values should visible when we choose on the "cat" in the same multidropdown field.

I strongly recommend against this approach - it would be nearly impossible to manage, and also not a good user experience in almost any case I can think of.  Instead, you should consider having a heuristic conditionality set in a local variable to detect when "cat" is selected in the initial dropdown, and when it is, show an additional dropdown consisting of the additional selections you want the user to be able to choose from.

sireesha said:

if we choose "cat" from the choice values then again another multifield dropdown values should visible when we choose on the "cat" in the same multidropdown field.

I strongly recommend against this approach - it would be nearly impossible to manage, and also not a good user experience in almost any case I can think of.  Instead, you should consider having a heuristic conditionality set in a local variable to detect when "cat" is selected in the initial dropdown, and when it is, show an additional dropdown consisting of the additional selections you want the user to be able to choose from.