We generally use Kayak when booking flights as they tend to be the best option for us since we aren't frequent flyers.
We are looking to book business class flights to Orlando in November out of Dublin and via London.
On Kayak we can get a great price by using the round trip search - Dublin - Orlando.
However we want to stop in London overnight on the way out and take in a show as a surprise for our daughter. To do this we need to use the multi-city search option of Dublin - London, London - Orlando, Orlando - London, London - Dublin.

The price is much the same and includes most of the same flights.

What I need to know is if I book using the multi city search is each flight classed as a single flight and so on the way back from Orlando would we need to retrieve our baggage in London and then check them in for the onward flight to Dublin or would the return be classed as a through flight.

I hope I've explained that ok.