Only have ONE pair in that small of a tank, otherwise there will be agression. The kribs and festivums might be okay, but not with FM's. The only thing I would put with a pair of breeding FM's in a 35 gallon is dithers.
I had four festivums and 6 Thorichthys pasiones in a 27gal long (36 x 12 x 13). As they grew and paired up I removed the other fish. So far, the pasiones pair, long male and two festivums are doing awesome together with all the other dither fish in there, which also includes a Black Ghost Knife and a Koi Angelfish. So it can be done...