Drinking and dressing up, and I'm sure there was more than one occasion of physical contact that would not be considered "PG".
From a European point of view everything a child could see in public spaces of Eurofurence is completely acceptable. It's just the US and some Arabian countries which claim to have a problem children seeing adults drinking alcoholic beverages. In fact, those countries seem to have a problem with anyone drinking alcohol or even just having fun outside the context of religious worship.
Again, the only reason why Eurofurence does not allow minors at the convention (with the rare exception to some few senior staff members) is legal liability for what a minor
does, not what they might see.
And besides, the decision whether to allow certain staff members' kids or not attending is completely within the competence of the board and nobody else's business.
Also, this pointless discussion is highly demotivating for the parents involved and the whole staff. We are dedicating most if not all of our spare time for Eurofurence, spend a lot of our own money on all those things the convention could not afford otherwise, work to complete exhaustion at Eurofurence itself, and all you can do is complain about a rare exception for an extremely important staffer who couldn't attend otherwise?!
Please drop this issue now.