LAs Totally Awesome from Dollar Tree + hydrogen peroxide, both full-strength. I use this on all stains that come out of a body. Spray the stains with both and let sit for a minimum of 30 minutes. Wash as normal. Assess stain before drying, and repeat if necessary. If stains were very light to begin with and it is difficult to assess removal while the clothes are wet, you can let them air dry but don’t put them through the dryer until you know it’s gone.
Truthfully though, I don’t know that it would really hurt it; I have gotten stains that were years old from clothing that had likely been washed and dried several times after it got stained. I do this all the time and have over 90% success on the first try, and nearly 100% success on a second try.
Try the blue original Dawn dish soap mix hydrogen peroxide and baking soda 1:2:1 ratio. That does pretty well for set in baby stains. Might take 2-3 wash cycles with that mixture in order to get it all the way out if it’s really set in though.