don't KNOW for Belgium but,
a friend brought a bottle of whiskey back from Bulgaria and the plane landed at Leeds before going on to Humberside.
All passengers had to disembark with their hand luggage and reboard.
The whiskey was confiscated.
I assume that the same would apply throughout Europe, possibly the world as these security measures are widespread.
Coming back from Goa we buy spirits in Goa and pack in hold luggage, any duty free is purchased in Doha rather than the Indian airport for this reason.

will you be collecting your hold luggage or is it transferred without you having chance to put the bottles in it?

We flew back from Costa Rica via Madrid in 2011. Despite the fact that our bags were checked all the way though, we had to go through security again at Madrid and all liquids (whether from duty free or not) were confiscated.

Brussels website says "Liquids purchased in the tax-free shops of a non EU airport or on board a non EU flight however are not allowed into the cabin even if they are packed in a sealed, transparent bag."

It seems nowadays you can't even bring duty free through another airports check in.

My brother even had a bottle of stem ginger in syrup bought in an airport in China(can't remember which airport) and had it confiscated at Schipol Amsterdam.

Thanks everyone. I thought that would be the answer. Seems stupid that you can't buy liquids airside to carry in your cabin luggage if you have a stopover. What do they think you are going to do if you are travelling airside to airside?

But are you definitely travelling airside to airside? The airport information site isn't very helpful but it makes clear that some categories of transit passenger actually need a transit visa even if they are never leaving the airport. This suggests to me that the reasons might be that:

A) All paseengers arriving from a departure airport from outside of the EU have to have their passports checked as they arrive at Brussels because it is the port of entry into the Schengen area?

B) International arrival passengers have to go landside on arrival at Brussels and then go back through security for domestic/EU flights?

The fact that you would be able to take purchases made post-security at an EU airport with you into the cabin when making a connecting flight suggests that passengers arriving from outside of the EU go through spearate security and/or transit routes through the terminal.

SM