No. One account, one login ID. Period.
You mention a "partner". Define that please. If you are referring to a joint 1040 return then there's no reason you can't share the login information with your spouse/partner.
If this is a business partner, then you can't use the online version of TurboTax to file a tax return for any business with more than one owner. You have to use the CD/Desktop version of TurboTax Business for that.
