Is it permissible to divide the reward for building a mosque between myself, my parents, and my siblings, and what should I do to achieve that?

It is permissible to include one's parents and others in the reward for building a mosque or any act of charity, although it is preferable for each of them to have a separate ongoing charity dedicated to them. Building mosques is among the greatest acts of closeness to Allah and ongoing charities whose reward never ceases, as the Prophet (peace be upon him) said: "When a person dies, all his deeds come to an end except for three: ongoing charity, beneficial knowledge, or a righteous child who prays for him." He (peace be upon him) also said: "Whoever builds a mosque for Allah, even if it be as small as the nest of a sandgrouse for its eggs, Allah will build for him a house in Paradise." This does not require verbal pronouncement; rather, the intention and purpose of seeking closeness to Allah on behalf of oneself and one's parents are sufficient, for the Prophet (peace be upon him) said: "Indeed, actions are but by intentions, and verily, every person shall have what he intended."