How to make a child object grow when the parent object gets smaller?

[glass lion]

I'm making a Rock Breaking system.
When you hit a rock, the rock's size is multiplied by 0.75x (This means the rock is now 0.75x smaller.)

But this also makes a problem for me. The child object with the rock gets smaller too. But I want the child object to stay the same size

How can I do this?

[lean lagoon]

I don't think that can be solve

Cuz I tried to make a script but all my attempts failed...

But I have some suggestions if you make a rock breaking system if the health of the rock reaches some point make it change the image of the rock