I'm working on the quest "For the republic part 2" and my problem is colonel Moore wants me to deal with the Brotherhood of steel. the thing is, is that i heard the only way to resolve it peacefully is to talk to macnumara and I put hardin in charge of the brotherhood and I really don't want to kill the brotherhood. Any suggestions?

Work with Yes Man.

At this point, only way to ensure the Brotherhood's survival is to screw the NCR over and work with Yes Man.

In the future, remember that Macnamera is the more peaceful of the two BoS leaders, and that Hardin is way, way more hostile to outsiders than Macnamera is.

okay thank you

Wow. So you'll help the Brotherhood over the NCR. Fair enough.