supportive while also helping the child know they can change their mind.

That you won't be disappointed if she changes her mind to something else.

One of my sons had taken a class (general elective) that turned out to not be as interesting to him as he hoped. It was one we were all excited about initially. It had sounded fun. He was stressed about going back for this new semester. We could tell something was really bothering him. We talked and asked and finally it came out that he wanted to change out but was worried we would be disappointed in him.
We honestly didn't care as long as he was interested and on track for college, but he felt that we were somehow invested in him completing the full year in this elective.