Construct a pedigree chart that displays the following information:
- Grandparents that do not have colour blindness
- A second generation consisting of 2 daughters (Ada and Brie) and son (Charles).
- Charles has 2 daughters, his eldest daughter has colour blindness.
- Colour blindness is an X-linked condition.

Using the information above, state the probability that Ada and Brie have colour blindness.