This theoretically is doable but will be a challenge. Your options will
also swing on whether the laptop you purchase will boot an old MBR
scheme or is restricted to GPT/UEFI. DragonflyBSD has instructions on
multibooting an older MBR.
https://www.dragonflybsd.org/docs/handbook/Booting/
If you need GPT/UEFI, then you choosing a bootloader that is capable of
GPT/UEFI dual booting. According to OpenBSD FAQ, Grub2 or reFIND
will work.
https://www.openbsd.org/faq/faq4.html#Multibooting
--
J. Scott Heppler
