Rule through the space underneath the previous entry through to the end of the double page. Then sign, date and time it in the usual way
Record the sensitive information on the following page(s) in red ink to make clear the fact of it being different from other entries – particularly when photocopying
Once the sensitive material is concluded, rule through any blank spaces to the bottom of the page, signed, dated and timed
You can then start recording normally on the next available blank double page