The tree model is an obsolete model, in my opinion. I would prefer to be able to asign no matter how many labels to a task, so I can retrieve it in several lists and reports (considering the Daily Targets a report from the DBMS point of view). This way, I would go further and be able to add several filters in the Daily Targets (I have seen this before, in the wish list, I think), this I would really appreciate! I would like to filter the information on the screen according to several criteria. From the GTD practice point of view, I would put a "@" filter, for instance (say, home or office or library) and also activate other filters (research, my thesis, the new article on bees or the admin things to do etc).
In a synthetic way, develop the label-oriented model instead of the tree-oriented one (a branch can have one and only one parent).
Thank you for your great tool and the efforts in this!