I'm not sure what your question is exactly, but "a subform on a tab on a form" sounds awfully crowded. Especially with a comments field.
I use an audit form with checkboxes. Depending on the selection for each question, a comment may be required. On the before update of each option group, I check the value and if it is "Unsatisfactory", a pop-up form opens for the required comment.
It gives me a lot more flexibility with space on the form.
You could even have the comment displayed in a label or textbox right below the yes/no option.
Of course, maybe space is not the issue. Post back with a bit more detail and we'll see what we can do.
John
Use what you have,
Learn what you can,
Create what you need.