You can already pair an array with an object by using containers. You can do more elaborate stuff by using uid's. For example your second example could be done like so:
on body created
--- create head
--- set body.head to head.uid
--- create arm
--- set body.arm to arm.uid
on body destroyed
--- pick head by uid body.head
------ destroy head
--- pick arm by uid body.arm
------ destroy arm
And you just use the pick by uid condition whenever you want to reference the child objects.
Edit:
In another way if you want a parent to have any number of children then you give the children a parent uid in the child instead.