Optional multiple email addresses in forms app

Hi there

I am developing a site currently that has an 'email a friend' functionality. It's all working ok but they want the option of sending it to 2 possible email address.

So, in the form options I have set this in the email address(es) field: {friend-email1},{friend-email2}.

When both are filled in, it works perfectly but if only one is filled in, it doesn't send the email. I need to make the second one optional somehow. I have tried merging them in to one address with a comma separating them but that didn't work (which I didn't think would, but you never know).

Is there anything else I can try?

Thanks..