Hi,
Been looking at flights on kayak, and under certain flights it tells you that different carriers will fly different parts.
Eg. DUB to SFO via LHR is with BA, but it says AA (for example), will fly xxxx
If I book a flight with BA (or anyone for that matter), on a site that doesn't show me this info, how do I know which airline will be operating it?
And generally, what portion will the other airline be operating?

If I booked a flight with BA, I would not expect an inferior airline be operating part of it.

Any advice welcome.