I have an external hard drive with a bootable HFS+ partition on it. I have unallocated space on this drive that I want to create a new exFAT partition on, so that my entire family's computers, both Macs and PCs, can use the new partition. I still want to be able to boot into the HFS+ partition from a Mac. I can only find sparse and/or conflicting information on this. On the one hand, I am reading about people not being able to access the exFAT partition from a PC unless the partition is actually created using Disk Management on a PC. On the other hand, when I try this on a Win7 system, I get a warning saying that the operation I selected will convert the basic disk to a dynamic disk, and I won't be able to start installed operating systems from any volume on the disk.
How can I create an exFAT partition on my external disk that is readable by both WinXP (SP3), Win7 and Mac, without losing the ability to boot from the existing HFS+ partition?