You must list your partner/spouse (if you are married) and all your children under 21 years on your DV Lottery application. Your spouse´s children must be listed too! Photos must be provided of all family members on the application!
This does not mean that all family members have to immigrate to the US. After winning, the principal applicant can decide who to take along or not! However, all family members must be listed on the initial DV Lottery application to avoid disqualification!