We have 2 high schools in our district. Here are some of the things we did:
Made sure the team did not favor one school over the other, picking team colors and name that was not from either school.
Have at key faculty advisor at each school. We also chose to have a student co-CEO from each school as well.
Coordinate transportation from one school to regular meetings. Ofiginally this was an organized parent carpool system, ultimately the district provided a dedicated bus
All the administrators are on the same page regarding the team, schoolwork and grades, homework during team travel - all the academics are very clearly the top priority.
Teachers know "those robot kids" as the ones who take responsibility and accept accountability (which buys them some slack at times), and team members are reminded often that their behavior reflects on the team at all times...
All the teachers also know who to go to when robotics gets in the way, and we make sure things go well.
Being in the same district, things like insurance and liability are simplified. We also meet at one school exclusively because they have the room for us. Every adult is either a teacher or has been through the background check process used for teachers (at team expense) - fingerprints, criminal check, etc.