If this is the offer you saw, the children are free on the Level 1 plan until 24th January 2011:
Comparison Information and Terms and Conditions
**Savings based on 2 adults switching from VHI Plan B Option to Aviva Level 2 Hospital and on kid’s cover commencing on Level 1 Plan from December 24th until January 24th compared to previous rates, reverting to €190 per child thereafter.
Level 1 Plan extends lower cover for hospital accommodation, day cases, overseas, and outpatient cover than Level 2 Hospital. For all differences between health insurance plans click here.