Hi Michael
You're right - there isn't a box for someone else. If your wife is able to make a mark on the paper - get her to make it. Make sure you have reminded them in the additional note page that you completed the form because she cannot do so. And you can also sign it and show both your names clearly underneath. Sometimes you have to point out the obvious to them.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
