144 Visa travel with Infant

Hi,
I (Italian) am travelling with my wife (Russian) and infant boy (Italian) to Shanghai by cruise ship from Japan. We will be there less than 144 hrs and then fly to Munich from Shanghai airport.
Our infant boy is less than two years old and travels on the lap in the airplane from Shanghai Pudong to Munich. He has a valid ticket, but no “seat reservation”. Is this a problem for the 144 hr twov exemption application and boarding of the cruise ship? We have eligible citizenship (Italian and Russian), passport expiry dates in 2020 and later and confirmed flight reservations with non-stop flight from Shanghai to Munich for my wife and myself with our infant boy on the lap.