While I can understand that they would find this upsetting, how long ago did their ancestors leave ? Are you sure that this doesn't stem from them having been u

While I can understand that they would find this upsetting, how long ago did their ancestors leave ? Are you sure that this doesn't stem from them having been used to self-identify as (American-)Croatian, but which hardly corresponds to the evolution of Croatians since then ? Their assimilation might be even harder than for some other immigrants without Croatian ancestry, if they feel like they might be "owed" something ? (And that's not even starting with other potential issues, like being of a different class...) Typically, first generation immigrants rarely fully assimilate (unless immigrating very young of course), it's their kids that will.