The parents of Madeleine McCann admitted it was "difficult" to allow their eight-year-old twins to enjoy the same freedom as other youngsters after their daughter went missing in Portugal six years ago.
Three-year-old Madeleine disappeared from an apartment at the Ocean Club in Praia Da Luz on May 3 2007.
Her parents Kate and Gerry McCann had left Madeleine and her two-year-old twin brother and sister Sean and Amelie in bed at the apartment while they had dinner at a nearby tapas restaurant.
The couple said it was difficult to allow the twins to enjoy sleepovers and school trips in the wake of her disappearance.
Mrs McCann told ITV's Daybreak: "They haven't had any sleepovers with school friends yet and I know that goes on a lot, although there is one potentially coming up soon so I have given my blessing."
Mr McCann added that the couple knew it was important for Sean and Amelie to be exposed to the same experiences as other children.
The couple said they have not lost hope that their daughter will be found and continue to campaign tirelessly for information on her whereabouts.
They believe the involvement of the Metropolitan Police now meant the hunt for their daughter was escalating, rather than grinding to a halt.
Mrs McCann said: "The search is very much ongoing. Nothing is slowing down, if anything I feel it's escalating with the work of the Met.
"And again it's just be vigilant, please still take your posters on holiday and don't forget about her, she's still missing.
"We haven't lost hope, our hope isn't any less than it was after the first 24, 48 hours."
Madeleine's parents said they did not yet know how they would mark the anniversary on Friday apart from a service in their local church.