My dad was a truly extraordinary story-teller. He could spin a fascinating yarn while thinking about a business problem... and very often, solving it. Quite amazing. But when he'd read something aloud to me, say from a book or the newspaper, he'd often play a kind of game. Somewhere along the story line he'd go off on a riff of his own. I think he waited to see how long it would take me to catch on and complain, "Dad-dee, that's not what it says. You're making it up!" Then he'd smile a special, mischievous smile.
I'd say there are two situations where diverging from the written text would be a good thing. Stories sometimes contain content that you intuit would be upsetting to your small child. So, be in charge and do a bit of editing. There's no rule that says you have to read every single word aloud. Fortunately, our brains are clever enough to allow us to read a bit ahead. Be aware.
Now here's the other situation. For very small children you don't need to stick to the words on the page at all. It's better for them if you simply explain and point out a little.
In my book 'Magical Motherhood' I actually recommend books without any words as a good place to start. These books by Magda Gerber are some of my most recommended, and much beloved of the grandsons. In addition, they bring an awareness of the seasons of the year, something which enhances the religious feeling as well as our connection with nature, as we know from Rudolf Steiner.
If I were showing a small child the page below, I'd simply say something like, "See, here's the little boy planting seeds" and point to the picture. "Here he's putting tulips in a vase..."
In this kind of 'reading' children learn about the world in a loving way.
