L.B.
After going through and manually undoing some tangles, have her start her downward strokes near the bottom of her hair, and then gradually start her strokes higher and higher, till she can go from her scalp all the way down. Starting the strokes near the roots/at the top of the head and trying to go all the way down from there just accumulates the tangles.
Oh, and with every stroke, she can fake a ponytail with her other hand, so the tension ends in her fist, not in her scalp!
Good for her. What a sweet thing to do, to give her hair to Locks of Love! You are raising a very generous and thoughtful daughter.
L.