This is very similar to the story of my life actually - except I'm a dude. I started swimming when I was young prolly before 5th grade and now am 26. I swam all the way through high school and my freshman year of college before switching to XC/track through grad school. I still did middle school track, high school XC, and the last two years of high school track. I went to a pretty good DII school and had some success nationally my last two years.
So my thoughts are If I had committed to running in HS instead of swimming I may have been recruitable - but my HS program was $hit so it is hard to say - its clear I was a better runner but was stubborn and liked swimming. As it stands I walked on to the DII program with 10:0X and 4:3X high school times.
I probably would have resented anybody in HS trying to tell me I was a runner not a swimmer so Its hard to say what could have changed the outcome. Best thing I can think of is get be more engaged/enthusiastic/encouraging with whatever she's best at but still let it be her choice.
Long post but here's a data point for you,hope it helps