as-salamu alaykum
for kaza namaz you only pray the farz rakat except for fajr. For fajr you have to pray sunnah as well. You should combine your zuhr or asr kaza namaz with zuhr or asr and samething for maghrib and Isha. For Fajr, you have to pray as soon as you get up; you cannot combine it with any other salah.
and Allah knows best
Ok it,s always the farz namaz but combination I listened to u first time