  In previous publications [arXiv:1608.08430, arXiv:1704.06502], the authors
have proposed Debye-H\"uckel-approximate free-energy functionals of the pair
distribution functions for one-component fluid and two-component plasmas. These
functionals yield the corresponding Debye-H\"uckel integral equations when they
are minimized with respect to the pair distribution functions, lead to correct
thermodynamic relations and fulfill the virial theorem. In the present
addendum, we update our results by providing simpler functionals that have the
same properties. We relate these functionals to the approaches of Lado [Phys.
Rev. A 8:2548, 1973] and of Olivares and McQuarrie [J. Chem. Phys. 65:3604,
1976]. We also discuss briefly the non-uniqueness issue that is raised by these
results.
