Thanks khallebal. Its a typo in the forum. I actually added that mistake to my post quite some time after the initial post, when I noticed that I’d missed copying that bracket from the 40_custom file.
I got it right there. 
Yeah, i realized right after typed my reply that an error like that should’ve been caught by grub itself.
I had to use something like this in my 40_custom file to get grub2 to see Haiku:
menuentry “Haiku”{
set root=’(hd0,4)’
search --no-floppy --fs-uuid --set xxxxxuuidxxxxxxx
drivemap -s (hd0) ${root}
chainloader +1
Of course, your mileage may vary!
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My problem was the fact that the Linux OS called the drive the 2nd drive (sdb) & the BIOS called it the first (hd0). Once I got that sorted & remembered to grup-update , all was good.
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