When asked about the aforementioned players, who are on loan at Valencia, Aston Villa and Crystal Palace respectively, Mourinho said: "Pereira is happy. He's playing. My only concern is that he's playing in a position that doesn't exist in Manchester United.
"We will need an update in relation to that. But the experience he's having, playing in a competition, in a good club with a big fan base, and with pressure around. I think it is an amazing experience for him and we are happy to let him stay there."
Regarding Sam Johnstone Mourinho explained: "[He is] at Aston Villa [and] is playing all the time and is an important player for them and they are going to fight for promotion. We are also happy to have him there.
"And Tim Fosu-Mensah's getting matches in Crystal Palace - so nobody is coming back," concluded the Portuguese.
Manchester United are not missing their three loan players, with the 'Red Devils' securing a 1-0 victory over Burnley in the Premier League on Saturday thanks to goal from Anthony Martial.