I think that 10PM was the last time that Nathan's mom saw him and spoke to him. If they'd had contact after 10PM, it would have been in the original timeline.
Original Calgary Herald Timeline:
"December 5, 2013: Alvin Liknes sells his Parkhill home to a Calgary lawyer. He continues to live in the home with his wife, Kathryn.
June 11-24: The Liknes family posts various ads on Kijiji during this time, advertising various household items and furniture for sale. The ads mention that the couple is moving and cant take these items with them. They also advertise an estate sale to be held at the end of the month.
June 27-29: Alvin and Kathryn Liknes hold an estate sale at their house. Signs on the front door say, come on in! Dozens of people cycle in and out of the home over weekend. Neighbours who chatted with the couple say they were talking about downsizing and moving to Mexico. Cherri Hodgins, a friend of Kathryn Liknes, said the couple bought a condo there and had been planning to move for several months.
Midday, June 29: Five-year-old Nathan OBrien goes to visit his grandparents with his mother, Jennifer. In the afternoon, neighbour Peter Waltons grandkids play with Nathan OBrien in the park behind the Liknes home, while Alvin Liknes looks on from the garage.
10 p.m., June 29: After staying at the house for an unknown amount of time, Jennifer OBrien leaves her parents house, and Nathan stays with his grandparents.
Its the last time anyone sees Nathan or his grandparents.
10 a.m., June 30:
Jennifer OBrien returns to her parents house to pick up Nathan. There is no one at the house. She calls police.
Late morning, June 30: Cliff Liknes goes to visit his brother, Alvin, after he didnt pick up the phone. He quickly realizes something is wrong when he arrives and sees police combing Alvins home.
4 p.m., June 30: Police announce they are investigating what they say is the suspicious disappearance of Nathan and his grandparents.
5:30 p.m., June 30: An Amber Alert is issued for the missing trio. The alert prompts numerous calls to police, but no significant leads turn up.
1 p.m. July 1: Nathan OBrien and his grandparents are still missing. The Amber Alert continues for a second day. Police dont know where the three missing people are and say they have a big mystery on their hands."
http://www.calgaryherald.com/Amber+Alert+Timeline+events/9991492/story.html?__federated=1