Air ticket and Kermasse

With Aelig going to school, organizing a trip to Malaysia is becoming more and more complicated.

I got the approval pretty easily, and my company allows me to pre-use my annual leaves.
It took hubby a longer time to get a go from his work, and since he couldn't pre-use his leaves, we have to leave in Juin. In France annual leaves go from 1 Juin to 31 May the year after.
Another constraint, hubby doesn't want Aelig to miss school for too long, so we have to go in July.
The best time to go was in August, as Aelig would be on summer holiday, we could celebrate Hari Raya in Malaysia, the baby sitter is on holidays.
But, starting from 1 Aug, prices go double or triple.
By taking in all these considerations, I almost booked the ticket from last week of Jun to first three weeks of July, until I popped up the million dollar question.

"When is the Kermasse?"
I actually don't know what is a Kermasse, but my MIL and hubby had discussed about the fact that Aelig would miss her first Kermasse and it seems that it was a big deal. Turns out, it is just an end of school year party. I didn't grow up having it so I didn't really think it is important. But hubby said it is a memorable moment for Aelig and we shouldn't miss it. So, we have to leave on the last day of Juin and everything changed.

1. We have to pay 250€ more
2. We have to let go of direct flight and take the one with a stopover and traveling time increases 5 hours each way.
3. We have to leave on Sunday and arrive in Malaysia on Monday when everyone works. It is less convenient for my family to pick us up.
4. There is no early train on Sunday to go to the airport. They have it from Monday to Saturday except Sunday. That means we couldn't take the earliest flight but have to take the one that depart in the afternoon.
5. This one is for me: I have to let go of Malaysia Airlines who propose yummy hometown in flight food.

Frankly, does anyone one really remember what was going on during a Kermasse when he or she was 3?