Can i downgrade via old backup?

[iMore Question]

I have a iPhone 5S and i have a iPhone 6. I will give my sister the 6, which runs IOS 8.4 and the iPhone 5S runs IOS 9.2... So if i backup the 6 and restore the backup on the 5S, will i get 8.4 on 5S?

 

[Just_Me_D]

No, you will not.