So MC has Saber Okita,
Archer Nobu belongs to the girl with the sailor uniform and bangs over one eye.
Lancer is already dead, but given that they described themself as one of the "Gert Krieger" it was probably a mass-produced Heroic Spirit Soldier and not the actual Lancer class Servant.
Ryouma + Oryou are here as Rider, and seem like they might be with the Counter Force.
I don't remember if we've seen Caster at all, but if the Lancer from chapter 1 was a Heroic Spirit Soldier then Caster is probably Maxwell, who was mass-producing them in the FGO event (GudaGuda 3). There's an unnamed Master in the Third Reich whose command seals were shown in Chapter 2, so by process of elimination he's the Master of whoever Caster is.
The blonde girl (German? Russian? Is she even blonde?) from the end of this chapter (she also showed up at the end of chapter 2 talking to Caster's Master) is probably in charge of Assassin Izou,
while "Major Shinji" (as koikun aptly dubbed him) seems to have Berserker Mori Nagayoshi.
It's a little hard to keep track of everything going on with the pace of updates (thank you for the work as always though, BananaShiki!) but the clues have been carefully laid out in front of us over time. Kudos to the author for that.