Can I stay logged in to multiple Y! mail accounts at same time? see details?

Sorry if this has been asked/answered, I haven't been here in months. I have 1 ATT/Yahoo email account plus a couple free Yahoo accounts- does anyone know if I can log in to my ATT/Yahoo acct. and then add my existing freebie accts as subs, and be able to go back and forth between them WITHOUT having to log... show more Sorry if this has been asked/answered, I haven't been here in months. I have 1 ATT/Yahoo email account plus a couple free Yahoo accounts- does anyone know if I can log in to my ATT/Yahoo acct. and then add my existing freebie accts as subs, and be able to go back and forth between them WITHOUT having to log in/out to use all of them? Currently all of my accounts have different PW's.

I hope that made sense. I'm a complete techno-loser, so speak very, very S L O W L Y ;)

thanks
Update: PS- can I do this without having multiple browsers open?
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