Hi. I suppose this is staff text (shift-X). When dealing with tied notes, use the caret before typing shift-x, or if you select the npte and enter the text, move it after the fact along the rhythmic grid ((cmd+alt+right arrox).
You’ll need to cut your text and enter the se ond part as a bew staff text. Dorico does not handle text flowing in different systems nor frames yet.
Shift-N in write mode invokes the caret. Double clicking in some areas also can bring the caret. And you can move it along the rhythmic grid with left and right arrows.
As explained above: Select the tied note, hit N for Note Input, move the caret (by using your arrow keys, for example) to the spot you want to paste it to, type Shift-X, paste your text and click somewhere outside the text box.
If you have the grid set to quarter notes, one keypress will be enough.
I would recommend not to deal with this until you have entered the piano part – depending on the content you might end up with a different scenario from what you have right now:
However, I would not complicate things. Just select the text you have entered, and alt+click it to bar 4. Then delete the text you do not need both in bar 3 and 4.