Since it has gotten cold and she has had to wear boots and not sneakers, she has moaned every day that they were too tight: I thought that she was just pulling my leg again. In the past, I could make her happy by pulling on the tongue or adjusting her socks (because the boots are not tight).
I took them off and played with them and put them back on: she still lives in a magical world where I can make her boots change size by doing so. But she complained again that one foot was too tight.
So I took them off to check.
Yes, one boot was 28/29 and the other was 30/31! I had bought both pairs at Tchibo last year, when the girls actually had different size feet (T2 is now only 1/2 size behind T1 and I'm guessing will surpass her next year).
I pulled out another pair of T1's old boots (T2 has 3 to choose among) and took her to kita, hoping that I had not donated the other half of each pair to charity (or friends) already.
Took about 15 minutes of digging and I came up with the other 2 boots— that's a relief!