At this time of year ,unless you've had the hobs castrated, they will fight if you put them in together . Even if you have had them done they may fight so its a matter of trial and error......but if they do start fighting don't leave them together they can seriously hurt each other . The other point to watch is with in-season jills.........they can become randy and start dragging the hobs about which in itself isn't too much of a problem but it can set up tensions in a communal group and the result is again fighting . With the hobs castrated I'd wait until they all come out of season (Autumn/