Thia is something which I didn't know when installing EasyBCD and, in the heat of the process, decided to install the program in all the multiboot OS's. That turned out to be helpful, since I was able to use the program to restore the multiboot after some problems, as long as I was able to boot at least one of the OSs, but it did seem to involve other potential problems.
I also thought that running EasyBCD installed in a different OS might be even more dangerous, so never tried that before.
After reading the above posts, I deided to try this way (using icon links to just one installation), and it worked well with W7-32 and W7-64, but not with XP, since XP doesn't work with v2.4, which is installed on the W7 partitions (didn't even try it in W10 yet).
So, in this case, the "link" procedure doesn't work, and I'm keeping v2.1.2 on XP, and 2.4 on the W7s. Are there other, better, possibilities?