I have always maintained that when someone is trying multi boot options of more than 2 operating systems then they should rely on a quality boot manager to do the work of protecting the MBR.
Windows boot manager just is plain garbage and will not work properly when multi-booting operating systems as it is locked to only being able to handle 4 partitions.
I personally use BootIt NG Boot Manager, Partition Manager, and Drive Image Utility - BootIt Next Generation
as it will handle as many partitions as you want or need and manage all the MBRs so that they maintain their own integrity.....meaning that the MBR is hidden from each operating sytem so there is no need of overwriting it!
I supplied a link to a free multi boot manager that has just come about and seems to be getting some good reviews...but I have yet to try it myself....But I am familar with some of the designers and trust their work! http://www.syschat.com/dual-booting-...oach-3197.html