answering my own question. Tried to purchase liquids twice in athens and both times they said since we were connecting in IST we couldn’t buy liquids as they were certain they would be thrown away. This is false info. Not sure if something recently changed with the new IST airport but when arrived we didn’t go through any customs or security. We did have to go through security at our gate and they said as long as it’s in a sealed bag from any duty free in the world, we were fun. Quite annoyed that I wasn’t able to but what I wanted but hopefully this post will help someone else