Yes, you can, if Kuvaverkko was the photographer for the other photos as well. You cannot combine photos from another photography studio in the same order with photos from Kuvaverkko.
You can add photos of another child to the same shopping cart by entering another photo code in the online store under Your photo codes - Enter photo code. Add all the photos of your children to the same shopping cart before confirming the order. Two confirmed orders can not be combines afterwards.
Search words: Combining orders, joint order