I am in almost exactly the same situation as you, Benny. My winners so far in a bet placed yesterday morning are Champagne Fever, Simonsig and Hurricane Fly, and the fourth leg is Arabella Boy.
I had thought that because the last leg is now going to be run on a different day that AB would be treated as a non runner, and I think it unjust that I am locked into a bet on a race to take place two days later under what could be very different conditions. What if the horse doesn't take kindly to being away from home for two extra days, what if the going changes, etc etc?
As things stand I am guaranteed a return of around 600 on the treble and three doubles that have come up so far, but if AB was treated as a non runner the return would be a bit over 2000. On the other hand if AB wins on Thursday I'd win about 5400.
One way of looking at it is that I'm now being forced into a bet on Arabella Boy of 1400 (2000 minus 600) to win a possible 3400 (5400 minus 2000), i.e a bet at odds of slightly under 5/2 on a 9/2 shot.
I suppose the other way to look at it is I now have a free bet on Arabella Boy to win around 4800 (5400 minus 600). At its current odds of 9/2 that equates to a stake of between 1000 and 1100.
What to do...