Need To Merge Two Sign-up Forms Together

I have an ezine with two different editions, a European and North American. I've decided to merge the two forms into one to simplify the sign-up procedure. However, I can't get the thing working

Here is the code for the two seperate forms, which was created automatically by the excellent Max-eMail. I've tried to merge them with a radio button like:

Code:
<input type=radio name="lists[15]" value="1LitNorthAmerica" CHECKED> North American Edition
<input type=radio name="lists[14]" value="1LitEurope">European Edition
but the values in [] are different for the countries, sex, etc. (For some reason the "[14]" and "[15]" stop the radio-button working - can't select between the two)

Could anybody be so kind as to help me merge the two forms together?

Here's the code (I haven't listed all the world's countries in the drop-down box to save space):