Ms Duncan said the family continue to be contacted by “experienced groups offering to support our search”.
She said they were talking to them “about what they can do to assist”.
However, she added: “In order for us to employ their help, they need to have permission from the Spanish authorities.”
Ms Duncan added the family were “so grateful for your continued support to bring our boy home”.
Earlier this week, Ms Duncan told of her “pain and agony” after searches failed to find her son.
“Words cannot describe the pain and agony we are experiencing,” she said.
“He is our beautiful boy with his whole life ahead of him and we just want to find him.”
