Is it obligatory for me to tell my father that I have learned of the existence of siblings from him, or is it permissible for me to remain silent and leave the matter until Allah wills and my father informs me about them?

The questioner is keen on honoring her father, Mahmoud. She must ask about her paternal siblings, if she knows of their existence, so that she can fulfill their rights, such as maintaining kinship ties with them. Islamic law encourages knowledge of lineages through which kinship ties are established. Maintaining kinship ties can be through financial support, fulfilling needs, visiting, writing, exchanging greetings through correspondence, and similar actions. She is not obligated to ask her father about them, nor to inform him of her knowledge of them, unless she perceives a benefit in doing so.