I thought I had control of my chicken 'collection'
I planned two new hens every two years.
I followed this for two and a half years and had four, but then my D'uccle got killed today.....
Originally I thought 1 new pullet to replace her... but....
2 new pullets would be better because you shouldn't really introduce one hen at a time... but....
3 new pullets because I already have three hens, even numbers would be safer to introduce!
Now I'm thinking about breeds and thinking broody types because I already have enough good layers, that way I could just buy eggs for her to hatch to slowly increase my flock.... slowly....(HA!)
Or maybe just one broody then many.. many eggs and "only keep the hens", I can't help how many hens she hatches, right 
Good thing I'm already half way to enlarging my coop anyway!