Time Machine to usb

Hi Everyone - i hope you will be able to help me get htis whole backup strategy right!

My first question is this:

I have an imac and a mac book, both of which have currently been backed up by time machine to usb external drives. If i copy the backup from one to the other then connect this drive to the back of my MBL duo will I be able to continue using time machine? I don’t want to lose these backups, or spend hours transfering things unneccesarily over our wifi!

Hopefully this makes sense

you will be able to continue using Time Machine and the files on the usb drives wall not be removed

however, you will not continue the same backup you had…

Time Machine will start a new backup with the MBLD