I want to acknowledge the work of the Canadian Institute of Child Health, the Learning Disabilities Association of Canada, Greenpeace, the Canadian Association of Physicians for the Environment, the Canadian Association of Family Resource Programs and the Canadian Child Care Federation.
These organizations are important to this person
This is definitely correct as their want to acknowledge these organizations indicates that they find these organizations to be important. 
( z1 important :ARG1 ( z2 organization :mod ( z3 this ) ) :ARG2 ( z4 person :mod ( z5 this ) ) )