It may be WW1, not 2, but try this.
A few years ago at a school concert we (the audience) were split into two groups.

One group were asked to sing "(Pack up your troubles in your old kit bag) and smile, smile smile" chorus.

Then the second group sang "It's a long, long way to Tipperary" chorus.

Finally, the two were brought together, with Tipperary as a counterpoint to Pack up your troubles. It worked really well.

f you want to try it, start singing

Its a Long way, and "Pack" starts on the same beat as the word "Long"

No idea if the same would work with the verses, but might be fun trying

Alan B