additional dependents (adopted children)

I sponsored my parents 4 years back and just waiting for the embassy for further instruction, just recently my brother and his wife had a marital problem and my niece and nephew are now under my parents custody and we are advised just to adopt the kids under my parents name and we are now working towards the legalization of the adoption. Once the decision is finalized, can I include them in my sponsorship under my parents dependents. I am still on waiting game as to courts decision for the adoption and embassy for the result of my sponsorship, thus I cant inform the embassy regarding this possible addition. Anyone can help as to what is the best thing to do? help and advise much appreciated.