Reply To: Swap between lines of text — GREP?

As I’ll be leaving shortly, I assume the text is as-is. Try this:

Step 1: This find/change should not be repeated throughout the document. Should be run once only.
GREP Find/Change:
Find What: (^Line \d\u.+\r)(^Line \d\u.+\r)(^Line \d\u.+\r)
Change to: $2$3$1

Step 2: To apply style to the first line.
GREP Find/Change:
Find What: ^Line \d\u.+\r(?=(^Line \d\u.+\r){2})
Change Format: Paragraph Style 2

Let me know if this works for you :)