Marcus Rashford and Alejandro Garnacho are among five players to have informed Manchester United they want to leave the club.
Antony, Jadon Sancho and Tyrell Malacia are also looking for a move away, with United allowing all five more time to explore their future options by delaying their pre-season return until later this month.
BBC Sport has been told the club will welcome the players back to Carrington if their futures are not resolved, allowing them access to medical and training support.
Rashford had previously indicated a willingness to return for the start of United's pre-season preparations on Monday.
The 27-year-old England forward was exiled by manager Ruben Amorim in December and spent the second half of the season on loan at Aston Villa.
Amorim had also told Garnacho, 21, he will be allowed to join a new club in the summer after the Argentine was left out of the squad for their final game of the Premier League season.
Sancho, meanwhile, returned to Old Trafford after Chelsea paid a £5m penalty not to sign him on a permanent basis following a season on loan at Stamford Bridge.
Brazil winger Antony was on loan at La Liga side Real Betis last season, while defender Malacia spent the second half of the previous campaign at PSV Eindhoven.
United's first pre-season friendly is against Leeds on 19 July in Stockholm before they go to the United States for the Premier League Summer Series friendlies.
Brazil forward Matheus Cunha will wear the number 10 shirt at Old Trafford next season, having completed a £62.5m move from Wolves last month.
Rashford had worn the number since 2018 after inheriting it from former Sweden striker Zlatan Ibrahimovic.
But with the English forward's future uncertain, the club have handed it to Cunha, who has signed a five-year deal, with the option of a further 12 months.
It is understood United made Rashford aware of the decision in advance. The club value him at £40m but are yet to receive any bids for the forward.
In February Amorim said he "couldn't get Marcus to see the way you're supposed to play football and to train the way I see it".
Rashford, who has scored 138 goals in 426 senior games during 20 years with United, said last month he would like to play alongside forward Lamine Yamal at Barcelona.
He made 17 appearances for Villa on loan, scoring four goals and providing six assists.
