The Appalachian dance tradition has a bunch of two-couple
figures. See, for example,
http://www.bubbaguitar.com/squaredance/littletoc.html
http://round.soc.srcf.net/round/dances/krs/guts
Usually they'd usually be used in a context where pairs of
couples dance together and then one or both couples in each
pair move on to dance with a new couple, either by orderley
progression around the a square or a big circle or by a
scatter promenade. In a pinch, ypu can use them wit just
two couples.
Teach a few figures. Call them in any order. For asymmetric
figures let give both couples turns at the "active" role.
Mix in some use of "I'll swing yours and you swing mine" (or
whatever words you want to use to say that) then "Swing your
own; leave mine alone" (or some other way of saying the same
thing), or just call the first swing and then have them keep
that one as parter for a while and dance some figures in the
new pairings.
--Jim
