See, these are all problems that I've come up with, too.
Basically, I need something that requires a 'forced escort' so that I have this big Lily/Snape/James triangle fiasco. (i.e. Lily wants to go with Snape, Snape doesn't want to go, James wants to go with Lily, Lily goes with James, Snape gets jealous, fin.)
Maybe there is a private party being held by Slughorn in welcoming to new Durmstrangs? Slug Club kids welcome the Durmstrang students, a chance for Sluggy to have a pary, which he likes, and also for him to scout out the Durmstrangs, see if he likes anyone, etc. I'm sure Lily was in the Slug Club, James for being clever, handsome, popular, and talented (I'd always imagined James came from an old money, well-respected in the right circles sort of Pureblood family that Slughorn would have been interested in.), and Severus, for his Potions skills and obvious talent with spellwork. So, Sluggy is scouting Durmstrang students to find new, international members to his club, Lily wants Snape to go with her because she can't stand Sluggy's parties or something (maybe she can only tolerate them with her best friend?), Snape doesn't want to go because Sluggy always pays more attention to Lily and James and he finds the man revolting, and James wants to take Lily.
And also a thing to think about: during this time in the Muggle world the East was still going through the throes of dictatorial communism. How would this have filtered into the Wizarding world? Would it have all? Would this influence maybe some students leaving the East for the more politically free UK?
That's a really good idea, SiriuslyMental! I've already written into the Chapter a bit about Lily and the Slug Club.
Plot Bunny! Must go run and write!