Ok I did do a search and could not find the answer, but I could be blind!!

I have a booking next year to South Africa, on the same ticket it is First to JNB and back with some Comair flights in Business as thats the highest class in the middle and then a connection from LHR to MAN at the end.

I am assuming comair flights are not preselectable even if I wanted to pay. MY thought was I can select my First seats but what about my connection to MAN, as its on the same ticket as a First flight can I pre select my seat or would I have to pay the fee?

On this occasion the booking is on miles which was good as I got the comair flights with it as well, but if you have to pay for seat selection on the MAN connection when you pay for a First seat that would seem a very bad move by BA as it is taking the ... somewhat!