Baggage allowance on connecting flights
From Aer Lingus website:
For Aer Lingus journeys between North America and the UK or Continental Europe, the long-haul checked baggage allowance will apply for all flights within the itinerary, unless there is a stopover of more than 14 days in Ireland, then each flight within the itinerary will have the relevant shorthaul or longhaul baggage policy applied to that part of the journey.
Given that connecting flights from SEN will be operated under EI flight numbers, the above should apply?