I wouldn't class a wedding as a "special reason" - if you want school age children to attend then don't hold it on a school day during term time!
Sirzy, I don't expect my brother and his intended to make their arrangements around the schooling of my daughters. I would get slammed on MN if I did for one thing!
And it's not an "abroad" wedding as it goes, as I'm travelling to the country of residence of the happy couple. It's me that lives in forrin.
Anyway, my point is, taking a five and four year old out of school for two days for a special family event (they are the only grandchildren/nieces, nephews etc), shouldn't really be an offence that incurs a fine. It's just not going to cause irreparable damage to their education and frankly, if they were sick on those two days, no-one would be complaining about the inconvenience to the school.
And no, I'm not going to lie or ask them to because a) it's wrong and b) there is no way on God's good green Earth either of them are NOT going to spend months talking about being in the wedding (which is why they have not yet been told!)