I would let her know you are there but let her find her own way.
It's hard as you are well informed however if she is trying to disprove you it's not really that beneficial to her.
Going through this journey my self for the first time (as in getting this far) I find the amount of advice I get can be overwhelming and at times annoying! Not saying you are and I think sometimes like everything in life people need to trial and error to see what works for them.
You sound like an awesome big sister though x