This is probably impossible but...
We have a local 2010 farm and HQ has one. I've been asked to use the HQ MySites service application rather than doing our own, which is very sensible.
However, on our local farm we're using a local domain: UNDPNT, when we go to the HQ intranet we're using our UNDPCO credentials.
What's the scope for the HQ farm's MySites application recognizing that a user logged into our local domain as being a matching member on its domain?