it looks like you are forwarding your AT&T Yahoo! emails to your GMail account.
yes, you can setup a new sub-account under your primary AT&T email ID. without setting up the forwarding feature on this new sub-account, you can send/receive emails on the AT&T mailbox.
to create a sub-account, just go to att.yahoo.com/membercenter website. then login using the master ID. go to the ACCOUNT AND BILLING tab --> click on the CREATE SUB-ACCOUNT button.
hope this helps!
Yahoo and AT&T email accounts unmerging – Things To Know
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