completed the personal details form of my dependents using the below trick,
Use the browser inspect element
1. Go to primary applicant's personal details -> Immigration history and citizenships section and inspect the HTML of the province and postal code
2. Copy the HTML of the province and postal code.
3. Go to dependent's personal details -> Immigration history and citizenships section and paste the copied HTML below the country of residence HTML
4. Enter the required values and click "Next". This will save the details.
Now click "Save and exit" and the dependent's personal details will be complete.
Note: If you are required to edit the personal details of the dependent again and save, you will have to do the same steps.