Our son is a lieutenant colonel in the Air Force and is marrying a girl who's a lieutenant in the Navy. Do we use their military rank when wording the rehearsal dinner invitation, or do we just say "David and Tara"?
There's no official military rule that says you should include your son's and future daughter-in-law's military rank or service branch on the rehearsal dinner invites. This is because the rehearsal dinner invite is considered to be a much more casual party than the wedding reception; it's not an "official command event" by the military, so to speak. "Tara and David" will work just fine.
That said, the military does dictate how a formal wedding invitation should be worded (which usually means including both their rank and service branch). So, in their case, the wedding invitation should read something like this:
US Air Force
Hope this helps!
Rehearsals + Brunches