From a female who did go from Conventional to Semi-fingertip to Fingertip. (It was 24 or 25 years ago, but I recall it vividly.)
I did not trust myself to be able to hold on to the ball with fingertip. My pro shop guy really wanted to see me move up to fingertip. As a compromise, we agreed on semi. To be very honest, it wasn't long and I was only putting the fingers in to the first knuckle. Semi is not comfortable and does not allow any better gripping.
My suggestion is to get a used ball and have it drilled full finger tip for her to try. Make sure she relaxes the thumb, another problem I had making the transition. I was afraid I'd drop the ball and gripped so tight with the thumb it wasn't coming off. A teammate had me hold the ball at my side and relax the thumb to show me it would not just drop off. After that I was fine.
I hope this helps in making the decision.
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USBC Bronze Coach "I cannot change the direction of the wind but I can adjust my sails to reach my destination." Jimmy Dean
Quaker 10/93 - 4/07
Quaker