Find another CM, and not all CMs do discounts for siblings, I don't, so taking siblings is not a problem, I often have.
In September I will drop off 4 children at school 5 miles away which means putting all 6 children in the car, go back at 12 o'clock and pick up the two that have started reception (They only go half days for the 1st term here) and back at 3.00 to pick then elder two up. Its part of the job.