  Magnetic skyrmions have been the focus of intense research due to their
unique qualities which result from their topological protections. Previous work
on Cu$_2$OSeO$_3$, the only known insulating multiferroic skyrmion material,
has shown that chemical substitution alters the skyrmion phase. We chemically
substitute Zn, Ag, and S into powdered Cu$_2$OSeO$_3$ to study the effect on
the magnetic phase diagram. In both the Ag and the S substitutions, we find
that the skyrmion phase is stabilized over a larger temperature range, as
determined via magnetometry and small-angle neutron scattering (SANS).
Meanwhile, while previous magnetometry characterization suggests two high
temperature skyrmion phases in the Zn-substituted sample, SANS reveals the high
temperature phase to be skyrmionic while we are unable to distinguish the other
from helical order. Overall, chemical substitution weakens helical and skyrmion
order as inferred from neutron scattering of the $|$q$| \approx$ 0.01
$\r{A}^{-1}$ magnetic peak.
