Madmare77
I am so sorry you are going through this - with Thomson AND this thread! It is an awful situation to be in and sadly because the airlines took advantage of anxious parents wanting to ensure their children are next to them on a flight, they saw fit to provide everyone with a 'pay up front' option to book seats - basically an extra buck or two for the airline! Parents and others KNOW that if they don't pre-book they would end up in the situation of being split up. Sadly for you, this could very well be the case.
This isn't YOUR fault for not pre-booking. Why should you? The airline know who is going when you book and therefore should automatically allocate seats when you do book. It is simply a money-spinning scheme!
We're flying with jet2 next week. It cost us £90 for us to allocate our seats and to ensure my 5 year old and 2 year old sit with us, their parents. I begrudge paying it, but I too would have been stressed if I hadn't and relied on the airline to sit us together. But in not doing so, disrupts everyone else! It is a catch 22 situation.
It also happened to DH and I when we travelled with United Airlines to Charlotte Airport in 2011. We were split, we asked to be allocated seats together (I am a nervous flyer and to be without my DH on a trans-atlantic flight freaked me out). The airline called us to the gate and issued us with new seats!
You never know! Someone WILL LIKELY take pity on you and ensure your 9 year old is sat together.
If airlines need to make an extra few quid then they should build the cost of pre-booking into the cost of the holiday and allocate seats at the time of booking.
But that would be too easy for them!