  We prove that the variance of spin overlap vanishes in disordered Ising
models satisfying the Fortuin-Kasteleyn-Ginibre (FKG) inequality under a
uniform field, such as generally distributed random field Ising model, site-
and bond-diluted Ising models with the Bernoulli distribution. Chatterjee's
proof for the Gaussian random field Ising model is generalized to other
independent identically distributed quenched disorder under a uniform field.
