At least as often as deletions or blackenings, there are overwritings or inserted text passages written between the lines. It is useful in two aspects to clarify at the beginning of a project how these cases should be handled.
In this simple example you can see how we handle such cases.
Since we include erasures and blackening in both layout and text, it is a logical step to treat overwrites and insertions in the same way. Usually, such passages are already provided with separate baselines during the automatic layout analysis. Every now and then you have to make corrections. In any case, each insertion is treated by us as a separate line and is also taken into account accordingly in the reading order.
Under no circumstances should you transcribe overwrites or insertions above the line instead of deletions. This would falsify the training material, even though the presentation of the text would of course be more pleasing to the human eye.