To take the famous phrase: "It's the Slots - Stupid" To IAG, nothing else matters, slots and routes, even if they have to flip them around between fields and trade some out and in.
Look at the BA history of buying up UK regional carriers and then usurping the EGLL slots (Brymon and Manx to name but two - and there were many.)
The a/c can be disposed of the people absorbed and retired as needs be. IAG need to show GROWTH and if you buy in growth - it still counts. Not really but they will show that it does.