Upvote:3
According to https://france-visas.gouv.fr/en/web/france-visas/airport-transit-visa :
You are travelling from an airport in a country located outside the Schengen Area and staying in the international zone of an airport located in metropolitan France while waiting for your connection to your final destination, which is also located outside the Schengen Area.
You must apply for an “A” airport transit visa (ATV) if you hold:
(…)
An ordinary passport issued by: (…) the Philippines (except in the case of seafarers holding a seaman’s book issued in accordance with international conventions)
(Emphasis mine)
So, provided both flights are on the same ticket, they are checked through to their final destination, do not need to exit the airside area, and hold a seaman’s book, then they do not need a transit visa.