After looking through implementation of Qt positioners (qquickpositioners.* in qtdeclarative) I have found that the positioning itself is done in updatePolish method while in itemChange and onCompleted methods positioning is schedule and polish is called. At this point I don't completely understand how it works, but it resolved my problem and I didn't have to resort to using qt private modules.

The QTableWidget is item-based. meaning you insert the data into the widget and it takes control of it. (owns it) So sharing between QTableWidgets is not really working. However, the QTableView is a view-model object. Here your data lives in a object (the model) that the QTableView asks for data. It is possible to share this model between QTableViews and if you update any field, it would be the same for all as "playername" would only exists once. So if you have not,please read about QTableView and Qt's model/view framework. If only player name is shared, then using a model might be a bit overkill. Still super flexible.