Jose,

>I know that I could suggest a "default" client, but it doesn't make any sense, sice there are more than 10.000 client's in the database..
>
>Any tips would be great.

Without seeing your application it's hard to tell you what is "best", but one possible option is to create a "dummy" client record with a nickname of " (Unselected)" with blank name, country and city fields. Notice that " (Unselected)" has a space in the first character so that it is always first in the list alphabetically.

Regards,