My daughter is Alhumdulillah 9years and fulfilling her wajibats
This ramdhan month is first for her after entering in wajibats. Usually I made her practice fasting but 15 to 18 per month till last ramdhan month.
She becomes exhausted and has headache, nausea and eating is poor during fast. Can I not force her to keep whole month and revert remaining fast until next ramdhan month?

Let her start practicing fast some days during Rajab and Sha’aban, and she will be able to fast the whole month of Ramadan, Allah willing.
This is what I did with my 3 daughters, and none of them missed a day since then