Originally Posted by
Peedtm
Changing the wheel size will put her lower to the ground. That is all. It wont shorten the seat tube or top tube. Only standover will improve.
You should keep your bike and buy her a bike that fits her.
+1
Though, if you wanted to make it more comfy for her, supposing she is set on riding the track, you could put risers on it and a shorter stem. possibly a positive rise or no rise stem (like a mtn bike stem) and risers would put her position considerably more upright.