Hi Wendy,
Nicole will probably have her own ideas on this and might be able to intervene directly for you but in the meantime this might help:
I used to have one account for posting (displaying a 'public' email address) and another for receiving emails to my usual non-public email address. That separation is no longer necessary as the new system doesn't automatically display your registered email address but allows you, separately, to display a 'public' email address of your own choosing, if you so wish. I decided to swap the email addresses on those two accounts so I could consolidate on one account and allow the other to lie dormant.
To swap the email addresses I assumed that the system would not allow two identical email addresses on the system at the same time, as they are used as unique account identifiers. So, I went through an intermediate stage, briefly using a third, temporary, email address for the changeover.
I also assumed that it would be less confusing for the system if you sign-in and out of each account separately at each stage of the process. (It might be worth you doing this on each account before you start just to make sure that you're definitely signed-out of both accounts before you start. ie that one hasn't been inadvertently left open.)
Most people won't have more than one SV/Undertow Message Board account, but for any that do, who face the same difficulty, this is my suggestion:
To: Swap email addresses on separate accounts
Stage 1) To change your email address on your first (eg wendy_o) account to a third, temporary, email address
Sign in to your first (eg wendy_o) account using its current email address and password. Click on My Account at the top of the screen and then click on Edit My Account Settings. It's slightly confusing but where it says Email Address, displaying your current email address, overwrite it with a third, temporary, email address. (This probably wouldn't be sanctioned as 'official' advice but if you don't have a third one you could just make up an email address, say a Hotmail one, to use for a few minutes.) Enter your password below and click submit. When you get the message to confirm that the change has been made you can sign out. It says that the change may take 10 minutes to take effect but I found that it changed immediately.
Stage 2) To change your email address on your second (eg wendy) account to that which was previously used by your first (eg wendy_o) account:
Sign in to your second (eg wendy) account. Click on My Account and repeat the above procedure but this time entering the email address that you were previously using on your first (eg wendy_o) account. When the change has been confirmed you can sign out.
Stage 3) To change your email address on your first (eg wendy_o) account to that which was previously used by your second (eg wendy) account:
Sign in to your first (eg wendy_o) account. Click on My Account and repeat the previous procedure but this time overwriting the third, temporary, email address that you used with the email address that you were previously using on your second (eg wendy) account. When the change has been confirmed you can sign out.
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These instructions might not be directly relevant to your own problem, particularly if you're finding it difficult to log in in the first place, but they might help if others are having similar problems.
Anyone else wishing to do this, particularly if they're intending to leave one account dormant, should also sign in to each account to check their Subscription and Profile settings, adjusting them as appropriate. The Subscriptions tab is at the top of the left side-menu. Your Profile can be reached by (eg) first selecting Message Boards from the Community drop-down tab on the right and then by clicking on your Sign-in /Member name, which should by then be highlighted (as a clickable link) in blue at the top of the screen.
Chris