A source told The Sun: "They will train together as a group but on a different schedule to the first-team. The first team will train in the morning. They will train in the afternoon."
Another added: "Ruben is determined to foster a new culture at Old Trafford. The players are all on board and he wants no distractions as they close in on the start of the new season. He wants to create an intimate team bond."
The club has informed all four exiled players to use the remaining window to explore exits, with the front office actively trying to generate transfer revenue. United are particularly interested in offloading Garnacho, who has emerged as a target for Italian side Napoli. The Serie A club is said to be preparing a £45 million ($60m) bid, although United value the 20-year-old Argentine at around £70m ($93m) and are holding out for a higher offer.