Hi @liamrobertsSP ,

>>>>>I have managed to do so with the "SIZE" attribute but the REF attribute is not following suit, might anyone have some advice? 

Can you share this block here?

>>>>I would like the Size attribute to alter, and feedback dimensions, each time the dynamic block is resized. What is the best way of doing this? 

In AutoCAD for Windows you can use BlockPlaceholder field with linear parameter Distance property inside attribute definition to create such attribute, but on Mac you cannot create BlockPlaceholder field. Attributes with BlockPlaceholder field will work on Mac, but you cannot create / edit them.

The workaround on Mac is to create attribute with "dummy" value and then change this value by replacing it with  Field with Distance parameter of the block.