**As a newbie would it be easier to model 1/2 or one side of the bed with a full size beds dimensions. Having each piece a component, from Window > Components, then select "In Model" click the detail icon to create "Save as a Local Collection". Then just import into a new instance of SU and use the move tool. To extend the width and length of each piece according to the new bed size you need. Then r/l select all and move~copy~flip the complete selection. Then explode each or all components to make one or each new size as your needs fit??

I am a beginner at best and roaming the forums as a alternate resource for tips and others applied SU`s concepts. This may seem obvious to most here but incase someone else comes across this. A few months back I would not have applied these steps and would have drawn out three completely different sized models.... I guest it is creating a refined workflow i.e.// work smarter not harder approach ...Peace.....**