Recovery CD's to USB with Etcher?

Hi, I’m using version 1.3.1 Etcher and have been swapping over to some Linux distros and loving leaving windows!! BUT would like to “save” my original windows recovery CD’s and also my recovery partition if possible to a USB in case I want to sell the laptops.

I have typically 3 or 4 DVD’s and I’d like to turn that into one bootable USB if possible, has anyone tried this?

Also I’d like to install etcher on a couple laptops and create a bootable USB from the hidden recovery Partition in those, has anyone attempted this? Then I can swap those over to Linux.

Thanks for any help (I’m pretty new to anything like this!)