No worries! That's fine. The only downside to summer tours is that your tour guide will likely be a day student, so they won't be able to give you a full scope of boarding life. However, the interviews aren't usually as time-constrained, so they are a little less pressure! I've toured family with babies, toddlers, grandparents, you name it! Bringing your brother won't negatively influence the way the admissions office sees you. Good luck!