Just thought I would post this here incase it may help anyone else who gets stuck with the same issue as me.
So I decided to install Haiku with a windows11/Hailku dual boot system on seperate drives.
The custom code required for grub2win menu entry needed these two lines.
search --fs-uuid --set=root 0D43-A2CE
chainloader ($root)/EFI/BOOT/BOOTX64.EFI
if you have followed UEFI Booting Haiku | Haiku Project as a guide then all you need to is replace “0D43-A2CE” with your own partition uuid which you can find using grub2win "list partition option.
Hi to the Haiku community as this is my first post 