In this answer, I used two hidden grey boxes, one after the other. However, I had some trouble getting them to format probably.
If you write
>! Line 1
>! Line 2
you get
! Line 1
! Line 2
In order to fix this, it seems that you have to place some text between the two lines. For example,
>! Line 1
$ $
>! Line 2
produces
Line 1
$ $
Line 2
as desired.
Is this necessary? If so, can it be fixed?