Your mapping is very complex (contrary to how it might look). I can't find a mathematical function to map between the two models. I know how the proxy can be implemented to work but it's not trivial. I'm unable to find a trivial solution to the problem and I've been trying for half an hour now. I'm close to coming to a conclusion that there is no deterministic function to map between the two models in Qt's model-view architecture - you always lack one piece of information - the row, column and parent are not enough to do the mapping.