You could insert a local „open“ time signature for that player only and create the lines within.
But that players staff will have no bar lines in the full score either, as you cannot hide barlines specific to one layout.
You have to hide - or if you can’t hide introduce a user defined scaling of 1% - certain elements, e.g. the 4/4 signature after the open time bar.
In the example I used line text which I believe is not suitable for this task: You are bound to the line style which is also used for other lines (You can’t modify this individually). Having the line text repeated after the system break in this case can lead to misunderstandings. At the end I would leave out the line text and use normal Text Shift+X,