Just received the form and I was about to just go online and select no changes - with just me as the UK citizen on there.
However, I read all the way through and I think they've changed our form. Previously it stated only to include people eligible to vote and gave instructions on who is eligible. However, now it just stated to include everyone living in the household over 16, a box to include nationality, and then another section to state anyone who is not eligible to vote and why.
After DW and I looked this over numerous times we have included her on it with explanation that she has ILR. Hopefully this will help any credit checks for her.