Discuss this with them. When housing students, pair them with the person that brought them. Who students see up front is vitally important. If the student group attending the weekend is ethnically mixed, then bring in a mixed team of staff and volunteers to lead singing, announcements, talks, small groups, recreation, and testimonies. Students need people with whom they can identify and know it is OK for them to be there.
Music is a big challenge.
It may take you years to develop a multi-ethnic worship service that really honors all who come. Count the languages represented by the students participating in the event. If possible, sing a song in each of those languages. See that it's well-taught. You'll be amazed at the number of languages, from Swedish to Spanish to Japanese.