Answered by Ustadh Tabraze Azam
Question: My family includes 4 members-2 adults and 2 kids. Do I have to give Qurbani for the kids or just the adults, or all four?
Answer: Wa alaikum assalam wa rahmatullahi wa barakatuh,
I pray that you are in the best of health and faith, insha’Allah.
The sacrifice (udhiya/qurbani) is necessary (wajib) upon the Muslim who is:  Sane,  Mature,  Resident (i.e. not a traveller), and  in possession of the zakatable minimum (nisab) in any form of wealth, above and beyond any immediate expenses. [`Ala al-Din `Abidin, al-Hadiyya al-`Ala’iyya]
Thus, the sacrifice would be obligatory upon anyone who fulfils these conditions. However, it would be permitted for one to appoint another (e.g. for the wife to appoint the husband) to purchase and slaughter an animal on one’s behalf.
And Allah alone gives success.
Checked & Approved by Faraz Rabbani