Is it possible to determine which of those destinations will be Stobart flights operated under the Flybe franchise agreement and which are pure Flybe flights?
The Flybe timetable will clarify. At present the E195 flights are shown as operated by "Flybe on behalf of Stobart Air". With the start of the winter schedule this changes to "Stobart Air". I am guessing this might be connected with Stobart putting the E195s on their own AOC.
I don't see anything particularly significant in this new announcement. The increase in the SEN fleet by one ATR72 and one E195 is already known. 230 flights presumably means 115 rotations per week, which is about right for 2xATR and 3xE195 in peak season. 15 destinations would suggest that three of last summers seasonal routes will not return, and the additional aircraft may thicken up the schedules on the remaining routes.