How do I base a style on another style?

I am using EndNote x7, and I need to create a style that is an exact copy of Chicago 16th, except that at the end it adds another field (Keywords). I don’t want to modify Chicago, as I need the ordinary version of it as well. Is there a way to make a copy of it and then modify it?

Thanks!

1.The first time you modify an output style EndNote saves it as a new file with the word “Copy” (e,g., Chicago 15th A Copy”) – or you can enter a different filename; or

 

2. Open the output style file then go to the EndNote toolbar and select File > Save as. (Refer to attached image.)