Unfortunately, the father of the groom often
gets largely overlooked at a wedding. He walks in behind his
wife and takes his seat and that is largely it. One way to
help the father stand out is for him to wear a tuxedo, like
the father of the bride, though he doesn't have to. It is
also appropriate for the grandfathers to wear tuxedos if they
choose to do so, but again they don't have to, though they
should wear suits.
In your case, if the step-father wears a tuxedo
and your husband doesn't, the step-father may be mistaken for
the groom's father. Therefore, it would be a good idea for
your husband to also rent a tux. He should wear one similar
to that to be worn by the bride's father.
Best wishes to you.
Glenna Tooman, ForeverWed.com Wedding