Before you proceed, you need InTouchApp installed on your phone & InTouchApp Extension installed on Chrome or Firefox. Learn more.
How to Save all Unknown Contacts from WhatsApp Group:
Step 1 - Open web.whatsapp.com in the browser and Scan the QR code by using WhatsApp on phone.
Step 2 - Select the Group from which you want to save unknown contacts.
Step 3 - On the top right side of the Chat screen on the Options bar, you will see a red contact icon - Click on the same.
Step 4 - It would show you the count of all the unknown contacts from the group. Click on SAVE NOW and you are done.