I am a canadian PR. My Sister and her husband from India have a valid canadian visitor visa. Their 2 kids (14 and 6 yr old) need to apply for visitor visa. Our proposed travel dates are during summer vacations (June 2025) for 3 weeks, so can someone share templates/format of letters we should get from kids' schools showing NOC/and that kids will be returning to school and not overstaying in canada?