AQ_OC said:
Turn on photostream on both devices and make sure they are on the same wifi network.
Doesn't the regular photo stream just upload the newest pictures?
I'd do a shared photo stream instead to manually send what you want.
-On your 4s, go to your pictures, click the edit button and select all the pictures you want to send to the mini.
-Now click on the "share" button at the top right of the screen and select photo stream.
-Create a new photo stream, name it, and in the "To:" section put the email of the apple ID you use on the mini.
-On the iPad mini, you should get a notification that someone is trying to share a photo stream, accept it.
-And TADA! All the photos you selected should be on there, and in the future, you can just keep adding pictures to the same photo stream. (It might take a while depending on how many pictures you have - make sure you are on a wifi network to make the process go faster and not use up your data.
-All these are still saved in the photo stream only though, to save them to your iPad, go to the photo app on the iPad, click the photo stream tab, and open the folder with the 4s pictures.
-Click edit and select all the pictures, then click the share button at the top right and select "save to camera roll"
Now those 4s pics should be on the iPads cameras roll