  A $k$-star is a complete bipartite graph $K_{1,k}$. For a graph $G$, a
$k$-star decomposition of $G$ is a set of $k$-stars in $G$ whose edge sets
partition the edge set of $G$. If we weaken this condition to only demand that
each edge of $G$ is in at most one $k$-star, then the resulting object is a
partial $k$-star decomposition of $G$. An embedding of a partial $k$-star
decomposition $\mathcal{A}$ of a graph $G$ is a partial $k$-star decomposition
$\mathcal{B}$ of another graph $H$ such that $\mathcal{A} \subseteq
\mathcal{B}$ and $G$ is a subgraph of $H$. This paper considers the problem of
when a partial $k$-star decomposition of $K_n$ can be embedded in a $k$-star
decomposition of $K_{n+s}$ for a given integer $s$. We improve a result of
Noble and Richardson, itself an improvement of a result of Hoffman and Roberts,
by showing that any partial $k$-star decomposition of $K_n$ can be embedded in
a $k$-star decomposition of $K_{n+s}$ for some $s$ such that $s < \frac{9}{4}k$
when $k$ is odd and $s < (6-2\sqrt{2})k$ when $k$ is even. For general $k$,
these constants cannot be improved. We also obtain stronger results subject to
placing a lower bound on $n$.
