How to help a kid who struggles with middle games

My 7-year-old daughter has not been improving (elo-wise) for a while, at around 900. She practices daily with a couple of rapid games against people, reviewing all games, plus a dozen of puzzles a day. While she is getting good at puzzles (fluctuating around 2100-2300 puzzle ratings now), I found that she struggles at middle games, often losing advantages (if any) after openings. Is there any way I can help her train her middle games? I feel her positioning concept is not quite there yet (rook at semi/open files, weak pawns etc.), and that she is having issues defending "defendable-but-real" threats. Thanks all for your suggestions.

https://www.chess.com/blog/TheMonkPlayingChess/the-first-step try this , maybe this can help

also if any other tips needed let me know