Why can't I add a person on Whatsapp's contact list to a group?

• To Add People to WhatsApp Group Without Saving to Contacts, make sure you have Admin Rights to the WhatsApp Group and follow the instructions below.
• Open WhatsApp and go to the Chats tab. Then press on your WhatsApp Group
• When you're in a WhatsApp group, hit the three-dots menu symbol and select Group details from the drop-down menu.
• Scroll down to the Invite through link option on the Group Info screen.
•  On the next screen, you'll notice a WhatsApp Group Invite Link along with the statement 'Anyone with WhatsApp can join this group by following this link.' Only give it to individuals you can trust.'
• Copy, Share, and Revoke Link options will appear below the message; tap the Share link option.
• On the resulting share menu, you'll see a number of alternatives for sending a WhatsApp Group link.
• You can use Gmail, SMS, Skype, and other methods to send the link.
• The Invite Link will allow anyone on WhatsApp to join the Group, but they will not be added to your Contact List.

Read More: Why I am not able to add someone to the WhatsApp group?