Scale to the parent object

child  = pickObject()
parent = pickObject()

if isValidNode child and isValidNode parent do
(
	
  about child.center
  (
		local target_scale = (parent.max - parent.min) / (child.max - child.min)

		if (abs target_scale[1]) < 0.0001 or bit.isNAN target_scale[1] do target_scale[1] = 0
		if (abs target_scale[2]) < 0.0001 or bit.isNAN target_scale[2] do target_scale[2] = 0
		if (abs target_scale[3]) < 0.0001 or bit.isNAN target_scale[3] do target_scale[3] = 0

		child.scale *= target_scale
  )

  
-- comment this line if you don't need to move child to parent center
  child.center = parent.center

)

It is possible that the parent can be not only a square, but also a rectangle.
It is desirable that the child was not tied to the parent.

and what would the properties of the child was loose, now they are blocked

sorry for my English, it's all mechanical translation :)

maybe this thread could help you

  scale child ((parent.max - parent.min) / (child.max - child.min))
  child.center = parent.center