Marciano Paynor, ASEAN 2017 National Organizing Council director-general for Operations, said Bolkiah will pay a state visit to the Philippines on April 27 and Widodo will make a state visit to the Philippines on April 28.
"When President Duterte called him up to congratulate him [Trump], had already indicated that he was coming in November".
In a phone call in December previous year, President Duterte invited then President-elect Trump to the ASEAN Summit.
Duterte had a hard relationship with Trump's predecessor, Barack Obama, as the former U.S. president criticized a series of killings tied to the Philippines leader's Drug War, prompting Duterte to tell Obama to "go to hell", calling him a "son of a whore", - for which he later apologized - and threatening that he might "break up with America". "I am nearly sure that the nine other ASEAN member-states will also be coming back in November", he added.
"Trump could skip much of the plenary (leaders do occasionally duck out to take bathroom breaks or hold the odd bilateral) but not without offending his hosts and indicating the very lack of engagement we'd hoped to avoid", he added.
As one of ASEAN's longest standing dialogue partners, the US plans to celebrate its 40 years of formal relations with the bloc later this year as the Philippines hosts the US-ASEAN Summit, a milestone in the partners' annual joint consultation meetings.
He is also due to travel to Australia.
"We usually expect 100 percent attendance", Paynor told reporters, when sought for confirmation on Trump's attendance on Asean summit later this year. "And numerous leaders who do not attend do so because they have internal issues and-which prevents them from coming", Paynor said.
The group's summit and related meetings will be held in Manila next week, the last week of April.
He said other Asean leaders may have a "pull-aside" with the President, if their request for a bilateral meeting would not push through.
Indonesian President Joko Widodo and Sultan Hassanal Bolkiah of Brunei will visit the Philippines and have bilateral meetings with President Rodrigo Duterte in April.