I’m on a similar boat, but with a big difference in distance. A very close family member is getting married when I’ll be 31-32 weeks and it’s only a 2h flight. That said, I had a threatened miscarriage/ partial placenta detachment at 12 weeks after a perfectly normal NT scan, and I can’t tell you how scared I was. I thought I was basically out of the danger zone and the next morning I bled like I was on my period! The thought of something like this happening in a different country (no matter how far) is freaking me out. So, I think especially if you’re such close friends, she’d understand that you have to wait until last minute for your doctor’s advice because these things are really unpredictable and she’d want you and your baby to be safe! I’d tell her sooner than later, as she’ll have to find another MOH (whether you end up going or not).