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Why? It seems a bit over complicated/ unnecessary to me. But maybe I'm missing something obvious.
And do you need multiple nicknames if you want to post in multiple local boards? I live on the border of 2 areas so they're both of interest to me.
Oh and while you're fiddling with local talk's new look can you make it more obvious how to navigate back to the main boards?
Regarding name changes What It'sAllGoingToBeFine said. When we asked Mumsnetters what they wanted from Local, one of the most common themes was protecting their anonymity on the main site while being able to meet Mners in real life.
If you want a nickname that makes you recognisable, you can just add a different premise like Nowismysleepytime.
You only have one nickname in Local, so you can post on as many sites as you like.
There's currently a button at the top right of the Local page sending you back to Mumsnet, but there will also be a link to Mumsnet Talk within Local Talk when tech has got that bit done.