Donna Wright, 33, from Hillside Court, is alleged to have used Facebook to send messages to Katrice Lee's family.
The little girl went missing on her second birthday in 1981 from a shop near a British army base in Paderborn, Germany.
Katrice's mother Sharon, from Gosport, Hampshire, and father Richard Lee, from Hartlepool, believe she was snatched and may still be alive.
Wright was not at Newton Aycliffe Magistrates Court for a brief hearing and the case was adjourned until January 16.
She is charged under the Protection from Harassment Act, and it is said that between December 2011 and November 2012 she pursued a course of conduct which amounted to the harassment by sending numerous emails and Facebook postings to the victims.
She remained on bail on the condition that she does not make contact with Katrice's family, look at the missing girls Facebook page or contact the pages administrators.
Katrice's disappearance is being reinvestigated.
Her family was out shopping for party food at a NAAFI store in Schloss Neuhaus, near the British army base where her father was a sergeant, when she vanished.
An image of how Katrice could look now, aged 33, has been created by a charity which helps find missing people.