If I understand your question correct you have a page with both a table and form fields. You would like to submit both the form fields as the selected item in the table. Unfortunately that’s currently not possible. A solution would be to devide it into two page as you already suggested. Another solution is to show a form field with a data-item instead of a table. That form field can be submitted together with your other form fields. You can even show data in the other form fields based on the item you selected in the data-item form field.
I hope this additional solution can help you