Four-year-old William, believed to have been abducted from the home of his grandparents in Kendall on September 12 last year, is one of the faces of National Missing Person's Week launched on Monday.

And the message from the family is clear - someone in the Hastings region must know something, someone must have seen something. Now is the time to speak up.

They are encouraging residents to be vigilant and keep the campaign message front and centre this week by placing red and blue balloons outside their homes - the colours of the Where's William? campaign launched in June.

On Tuesday, the Where's William? campaign team will visit Port Macquarie to launch the next phase of their search to find answers.

On the eve of Missing Person's Week, the family told the Port News that hope fuels their motivation to keep searching for the truth and for as long as little William remains missing.

"Managing the grief is hard, maintaining motivation to find our boy is easy," the family said on Sunday.

"We will never give up on William. Our motivation is that we will never give up. It's not an option. William needs to come home. We need to know what happened to our beautiful happy, funny little boy.

"Our hearts ache for him every day."

The family has made a heartfelt plea to the Hastings community to keep searching and to anyone with information, or the one person who knows the truth, to step forward.

"You need to tell your secret now, it's been too long," the family said. "William is loved. William is cherished and William is desperately missed by all who love him.

"There is a gigantic hole in our family, every single day we face those reminders of William being everywhere around us but he's not.

"Somebody knows something and if that somebody is you, please, please if you know something about William's disappearance you must call Crime Stoppers and tell them what you know.

"Even if you're not 100 per cent sure but you suspect someone may have been involved you have to make that call and let the police make that decision.

"If you do, you could be the person we are depending on. You could be the person who will have helped to bring William home to us."

Since the launch of the Where's William campaign just over four weeks ago, more than 15,000 people have liked the Facebook page which has spread the word about the toddler's disappearance internationally.

For information or to make a donation, visit whereswilliam.org or the 'Where's William Tyrrell? Bring Him Home - Official' Facebook page.

If you have seen William or have information relating to his disappearance, contact Crime Stoppers on 1800 333 000 or at Crime Stoppers online reporting page nsw.crimestoppers.com.au. You can remain anonymous.