Dear Summalevin,
in general, some conditions have to be met.
1. The children must be under 16
2. The children must hold a valid passport.
3. The costs of livelihood including health inssurance can be covered for all of you.
4. You have adequate living space (appr. 12 square meters per person).
Hope this helps. Please don't hesitate to get back us if you have further questions.
Best regards
mbeon-Christine