OK man, you owe me...I actually went digging through the Employee Handbook to get the straight answer.
According to the book, if your children reside outside the UAE for more than 6 months of the year, they are not covered inside their country of residence. It gives a specific example; "E.g. if you children reside in the UK/USA, they are not covered for medical in their home country." A provision is made, however, for children who have a UAE residence VISA but are studying at school abroad. (As an aside, I did learn that the coverage is better than I thought for your family as long as you're a UAE resident.)
I believe that what some guys do is bring their families in, get them a VISA and then send them back home for school.
Anyway, I don't think this is the answer you wanted, but that's how it reads.
BC