I use TDA and I've noticed multiple number issues since they started integrating Schwab. Gains before the bell that aren't real, pennies available for trading that don't exist and overdraw the account when used, inconsistent bid/ask numbers with refresh... They correct themselves, eventually, but it is annoying. I'm not switching though, yet, too much effort for something that might get fixed.
I have 3 accounts and they are all accessible under one login, or separately for 2 of them, but I needed to setup the account link, it was not automatic. Are you sure that the person with the other account didn't setup the link and/or can they see your accounts? You should call customer service, IMO.
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