Hello Piotrek,
Using your instructions, I copied pages.php from Integral-Pro to Integral-Pro-Child. Then I pasted the PHP snippet into line 27.
Here’s a 41 second YouTube video showing you how I pasted the snippet into line 27. Please watch it and tell me if I did the right thing.
Now here’s the important question: Does this mean that I can now insert a featured images into any PAGE and not just the posts?
Peter