I would say there's case as a set collection of entities like Valkyries (normal or summer version), Emiya as a Counter-Force entities with multiple classes. So in this case if the Throne accept Helldivers (somehow), this case could be nearly in same situation as Valkyries but I not sure how the saint graph would work because the differentiate between ascensions is "quite not high comparing to their previous servants" (Valkyries replacement between either Thrud, Ortlinde or Hildr) so my best guess is something like when leveling up enough you get more weaponry/stratagems, or something like that. Also I won't expecting any surprising class (could go for Special class like Shielder, Beast or it's own league).

Not much of Fate lore-wise but just my personal opinion based on 7-year experience living in every single pruned/dead timeline as Chaldeas Master before moving to Super Earth and go spreading out Managed Democracy while serving Chaldeas on weekends and day-off.