Forbidden Secret Realm [1]
There were four main groups who arrived at the Forbidden Secret Realm, but they weren't the only ones.
Aside from the four great clans who were participating, several smaller influences from the Eastern Region were given the chance to prove their worth through this expedition.
Their younger generations would experience trials and triumphs, and when they came out, they'd become people worthy of representing the Veritas Clan as its vassals.
Whatever rewards they gained inside were theirs alone. The Veritas Clan would never interfere and try to take a reward by force, but many chose to offer their gains to them regardless.
Otherwise, if the Veritas Clan truly desired something another party gained in the secret realm, they'd pay for it properly and give the clan in question a rise in status matching their achievement.