Sorry to be a pint in the b*tt but not working yet.
Leaving emtpy the domains gives me the original config which allows to me login in both apps but does not share cookies at all.
I assume that locally I cannot make it work.
I will try this once I have it uploaded on the clients domain and see if it works.
Is there anything else that might be avoiding the cookie sharing? I mean server config, anything?
Thanks for the support.