Update BnoC line-booking to adapt to changes in FT requirements

These changes were meant to be in !2300 (merged) but appear to have accidentally got dropped during on the of the rebases. This was spotted by @zewen and noted in #685 (closed).

I have cherry-picked here the relevant commit.

See this thread from !2300 (merged) for some details of the changes.

Closes #685 (closed)