If you have a JAR licence then there is no problem getting your seaplane rating from Aeroclub Como amended to your licence.
http://www.aeroclubcomo.com/
I did floatplane rating their and CAA amended it to my UK PPL without any problems. Even the French DGAC, noted for their obstructive bureaucracy, have said that they will accept it on my CPL next time I renew the qual, which really surprised me..