### Families of curves and alterations

In this article it is shown that any family of curves can be altered into a semi-stable family. This implies that if $S$ is an excellent scheme of dimension at most 2 and $X$ is a separated integral scheme of finite type over $S$, then $X$ can be altered into a regular scheme. This result is stronger then the results of [ Smoothness, semi-stability and alterations to appear in Publ. Math. IHES]. In addition we deal with situations where a finite group acts.