How can my sister's faith be protected and strengthened after her conversion to Islam, especially given our fear of our parents' reaction and their attempts to revert her to Judaism?

A Muslim woman should help her new Muslim sister remain steadfast in the religion by encouraging her to read and listen to the Qur’an, providing beneficial Islamic books, diverting her from bad company, supplying her with impactful audio recordings, and encouraging her to praise Allah for the blessing of guidance and to commit to prayer. She should also advise her not to reveal her conversion to her family at present, for fear of harm.