I have an old Gmail account that is bound to my Android cellphone and everything else.The old mail address is too long, so I made a new account with a shorter address.Now I tell people my new, short email address.I can check email forwarded from the new account using my old account(delegation).  But if someone were to invite me into a chat using my new account, how will I get notified and chat with that person, using my old account, as the new account without revealing the old account ?  How do I chat on behalf of another gmail account ?
Forward new Google chat requests to the delegation master account
gmail;google hangouts
Short answerAt this time isn't possible to chat  on behalf of a Gmail address but the users could have a chat session open for each of their Gmail addresses at the same time.AlternativesThere are several ways to have several Google chat session open at the same time:Use several devices.Use different browsers.Use several browser profiles, one for each Gmail addresses.Use Google multiple sign-in.Add all the Gmail addresses to their Android devices.ReferencesGoogle Chat HelpGoogle Hangouts HelpSign in to multiple accounts at once - Google Accounts Help