Flanker Megan Heath, number eight Daisy French and prop Jess Thomas all featured for the representative team.
French, in her final year at under-18 level, was making her South West debut and was among the try scorers.
Thomas, another final year under-18, also managed to get on the scoresheet.
Heath, meanwhile, is in her first season in the age group and so to earn selection for the South West and previously Devon was a major achievement.
Fellow Services players Boo Berry and Lizzie Cole missed out on playing for the regional team due to injuries.
Berry is recovering from a shoulder injury, while Cole has just returned to action follow a lengthy spell out with concussion.
Exeter Saracens’ Ellie Gilbert and Crediton’s Chloe Hetherington also played for the South West against the Midlands.