Aston Martin and Cosworth were among several new parties which sat in on a Power Unit Working Group meeting which took place earlier this week.
An initial working session devoted to F1's future power unit plans and held back in March was attended by representatives of the Volkswagen Group.
This week's meeting was held on Monday in the presence for the first time of representatives from Aston Martin, Cosworth, Magnetti Marelli and Zytek, according to Motorsport.com.
F1's sporting boss Ross Brawn is hard at work designing the sport's post-2020 engine rules and the meetings are likely a means of collecting views from all relevant parties as a foundation is defined.
All participating parties in the process have apparently agreed that F1's future engine format should retain its link with modern-age hybrid technology, albeit within a simplified framework.
A third meeting has tentatively been scheduled for September, before an assembly of the World Motor Sport Council, after which a joint proposal from the FIA and F1 regarding the engine of the future should be formulated.
In the interim, Ross Brawn will continue to meet individually with participants in the process.
GALLERY: F1 drivers' wives and girlfriends
Keep up to date with all the F1 news via Facebook and Twitter
Sauber driver Valtteri Bottas has been handed a three-place grid penalty for Saturday's Sprint race…
The action kicked off in earnest on Friday in sunny Miami on Friday, with Max…
Daniel Ricciardo has suffered a terrible start to his season with RB that left him…
Charles Leclerc expressed a sense of relief after securing a front-row starting position for the…
Lando Norris had been looking in stellar form throughout qualifying for Saturday's Sprint race in…
Max Verstappen admitted his surprise at securing the sprint pole position at the Miami Grand…