Thanks. JL has a message on the main page of their website regarding long wait times for the US contact center, due to “congestion”. Also a note that any changes to a booking made through an agent (such as BA) must be made by the agent.

I was able to select our seats in business class on the website, and provide personal details such as contact information, but could not get into the passport area. I’ve decided not to worry about it and just plan on airport check-in for both directions.