I would also suggest looking at
Stay-Focused (I'm the medical advisor for this organization) and
The DiveHeart Foundation - Home. Cerebral palsy alone does not pose a problem for scuba diving. However, children with cerebral palsy often have problems associated with the cerebral palsy that may pose a problem. For example, some children with CP had been on ventilators if they were premature thus causing bronchopulmonary dysplasia (which then causes problems like reactive airway disease/asthma). If severe enough, this may be a problem with diving. They may also have seizure disorders that would disqualify them.
Others may have ventriculoperitoneal shunts relieving pressure on the brain from excess fluid. Shunts have been shown to work at up to 4 atm of pressure and if your friend is planning on bringing kids down to only 10 feet, VP shunts should not be a problem (but not all manufactured shunts have been tested in hyperbaric conditions). If they have other implantable devices such as Baclofen pumps, then 10 feet may be deep enough to cause a problem.
There are too many factors to discuss in a short post. The point is that cerebral palsy alone should not be a problem with diving but medical issues associated with the CP may pose a problem. Each person's medical history needs to be evaluated individually in the context of diving.
It is wonderful that your friend would like to bring SCUBA to children who may otherwise not have the opportunity. I would be happy to discuss medical issues in more detail if she would like to contact me.