Newton’s law of gravitation
F = – G M m/r^2
is not a law of nature.
The law for the static gravitation
F = ± G Mg mg/r^2
could be considered as a law of nature with the conserved gravitational masses Mg and mg. The equation of motion in a static gravitational field, if the bodies are in rest, could also be considered as a law of nature, with the inertial mass, mi(body), and the gravitational mass, mg(body),
mi(body) a(body) = ± G Mg mg(body)/r^2.