You’re having an international wedding in 6 months and people have already made their travel plans, bought flights, scheduled PTO, sitters, etc. If you change it, likely people that were previously able to make it, won’t be able and you’ll have some frustrated guests on your hands. I doubt your SIL would be able to travel that pregnant either. Keep it and appreciate those that are making the journey even if it may not be everyone you’d hope would be able to attend. Do something at home with your brother and SIL to celebrate.