Thanks for everyone's help!
I'm pretty savvy with Partition Management & dual/ multi booting since Win 95/98/ NT days, partition table editing, VHD native boots, BCDboot etc and the UEFI vs BIOS install / boot in a Mixed OS scenario still messes with me. I need to do some intensive Re-reading to debug issues I'm facing on some Acer/ Toshiba laptops and their BIOS/UEFI options v/s Multi Boot OS on partitions.
Interesting. Wish there was a clear info graphic to CLEAR out this UEFI/BIOS - GPT/ MBR drama.