Thanks again for the update.
We have validated your query. Please find the validation details in below,
Due to the dialog is layout component, you cannot send and process the data with dialog component. But you can achieve mentioned requirement through component interaction from the application end.
We have prepared stackblitz sample to meet your requirement, please get it from the below link,
The above sample was prepared on the basis of the following constrains,
1. Created New child component (FormDialogComponent) and rendered dialog in that child component.
2. In the parent component (AppComponent), selected item data passed by calling child component public method with arguments, through the first dropdownlist select event callback.
3. Child component will receive the value from callback function and assigned to component variable
4. Once submit button clicked saved data item processed for condition checking and required output emitted to parent component.
5. Parent component receives the emitted values and update it to the second dropdownlist value.