Alex Scott, Rio Ngumoha and Josh King will travel with the England squad to the World Cup.
The young trio have not been included in Thomas Tuchel’s 26-man squad for the tournament in United States, Canada and Mexico.
But will travel with the group to Miami and join in training with a view to getting minutes in England’s two warm-up games, against New Zealand on June 6 and and Costa Rice on June 10.
Their inclusion is, in effect, to make up the numbers with Arsenal’s four Champions League finalists - Bukayo Saka, Eberechi Eze, Declan Rice and Noni Madueke - joining up later with the squad.
Crystal Palace’s Dean Henderson - who will next week compete in the Conference League final - will also link up with his team-mates later. Brighton’s Jason Steele would act as his deputy, if required.
"We will take some young players to train with us and keep the squad the size we need,” Tuchel confirmed on Friday.
"Alex Scott. Rio Ngumoha. Josh King. And there will be one more player we cannot name because it's not confirmed yet.
"But I'm happy these guys are with us, especially Alex who was on the list of 55 and had a disappointing phone call that he didn't make the first cut. But the reaction of him was outstanding, the wisht o be in pre-camp and close to the team, it wasn't even a question for him.
"I'm glad he's with us because it was a close call and he has a chance to get a first camp."
England will fly to Florida on June 1, where they will remain before taking up residence at their World Cup base in Kansas on June 13.
