Backlinks from my sites

Hi! I'm new to IM.
I have 2 sites on the same IP, that have pr2. (Group A)
Also there are 2 sites on other IP. (Group B)

I made a new MNS and I want to link group A and B sites to it. But there is the problem, that group A added to the same webmaster tool, where my MNS is. IS it safe to link?

safe way is to not interlink your own sites..

well as long as these sites are related, you can interlink them. If they both are of completely different niche, then you should not link them. I follow Matt Cutts blog regularly, I have seen similar example before.