The Red Devils will take on ASEAN All Stars in Kuala Lumpur on 28 May before travelling to play Hong Kong two days later.
One of United’s sponsors, Apollo Tyres, says Onana, Harry Maguire and Diogo Dalot will be in Mumbai, India on Thursday, 29 May for a meet and greet.
United’s international players will then join up with their national teams the following week.
Five days after United’s final game, Fernandes and Dalot will likely be involved for Portugal in their Nations League semi-final against Germany on 4 June.
United’s pre-season then begins with a match in Sweden against Leeds United on 19 July, before they fly to the US as part of the Premier League’s pre-season tournament between 26 July and 3 August.
They finally host Fiorentina on 9 August.
Amorim has previously defended the post-season trip, calling it a “small sacrifice” which allows the club to “make contact with our fans around the world.”
Defender Maguire has said: “It is the club’s decision and we don’t have any right to argue against it after the performances we have put on.
“As players, we have to take responsibility for the position in the Premier League and the money we have generated this season through that finish, which is nowhere near good enough.
“We don’t have a right to stand here and criticise the club for trying to generate some money that will hopefully help us next season with signings.”
Defeat in Bilbao means United will be without European football next season for only the second time since 1990, leaving a £100m hole in the club’s finances.
Last week, BBC Sport reported United have told some staff working at their Carrington training ground that they will lose their jobs, in the second round of redundancies since Sir Jim Ratcliffe bought into the club last year.
The latest cutbacks come against a bleak financial backdrop, with United losing more than £370m over the past five years.
Last season, Tottenham Hotspur and Newcastle United flew to Australia for a post-season friendly, which was described as “madness” by BBC pundit Alan Shearer.
The increased workload on elite players has been widely discussed this season, with all three European club competitions expanded this season and Fifa’s revamped Club World Cup starting next month in the US.
Former Manchester City defender Michael Brown told BBC Radio 5 Live’s Football Daily podcast: “At the end of the season, you walk around the pitch and you get that feeling of ‘I’m done, I’m finished’ and you want to go and put your feet up and have the mental rest before the international games. You look forward to the break.
“I understand why they want to do it financially, but it shouldn’t be allowed.”
Former England goalkeeper Paul Robinson added: “Not a single one of those players will want to go, but they are commercially obliged to go in their contracts.”
