SR loves horses. She would own one if she's allowed to keep them. So you can say that her horse t-shirts are one of her valuable possessions. She has several of them and most of them are getting shorter but not tighter.
To salvage one, I cut off the lower part of the shirt saving the main image (of course!).
I took one of her dad's old gray t-shirt (shhhh, don't tell him...), gathered it before adding it on.
The shirt is a little loose after sewing it together so I added elastic in the back (not pictured).
Here's a baby doll shirt that should last, hopefully, for a couple more years.