Can a non-Muslim girl declare her Islam between herself and her Lord and perform some prayers, such as Dhuhr and Asr, without performing the rest of the prayers due to the difficult situation at home?

A Muslim must perform the five daily prayers. If a girl fears her family discovering her conversion to Islam, she can combine the prayers secretly, limiting herself to the pillars and obligations of the prayer to perform it quickly, and perform ablution (wudu) discreetly or dry ablution (tayammum).

If she is unable to pray standing or facing the Qibla, she is permitted to pray sitting or lying down, gesturing for bowing (ruku') and prostration (sujud) or intending them in her heart, and praying towards any direction. This is because prayer is not waived for a legally responsible person, and because Allah does not burden a soul beyond its capacity.

These facilitations are based on the principle of necessity and fear of harm, similar to the prayer in extreme fear for a fugitive or a captive, where the prayer is performed in any possible manner.