Within my research, there are absolutely NO separate books by Frances Lockridge. She co-wrote books with her husband, Richard Lockridge. All Pam and Jerry North series are co-written, and should be listed under both Frances Lockridge and Richard Lockridge. He wrote some books independently before her death, and several after her death.
None-the-less, Richard and Frances are two separate people. Please list just one of them in the Author field, and the other as co-author in the Other Authors field. That way it will be possible to enter separate Common Knowledge for the two people.