There was no Joe as far as I can tell. She possibly* had two sons-- neither born in 1964. I'm not going to share their names here because that would be against the rules, but they are common first names starting with F and D. The F was named after her husband who is also F. Her husband appears to still be alive and was never named as a suspect in Kathleen's disappearance so I don't believe we are allowed to name him here.
*I'm saying "possibly" her sons because I'm basing this info on shared address history and DOB of people who lived with her. They are the right age to be her sons and one has a variation of her husband's name.