Thanks for your very clear answer! My point was basically, most or all of the interesting information is stored in the journal. You could hide the legder from

Thanks for your very clear answer! My point was basically, most or all of the interesting information is stored in the journal. You could hide the legder from a non-technical user, or even generate it on-the-fly. I think this is the distinguishing idea in OP's program. That the data model has only one "from" and one "to" field is incidential and could be fixed.