Behaviours: Add the ability to control Cascade field child options

When controlling Cascade field Options through behaviours, we need to also control the child field options.

e.g:

• We have a parent option AAA with child options A1, A2, A3
• and a parent option BBB with child options B1, B2, B3
• I want to restrict the child options of the AAA parent option to just A2, and A3