Upvote:0
It is said the Monks as the Buddha's children. Likewise, it can be considered that someone adhering to the dhamma becomes his relative. In this context, if you do not fall into the path of Dhamma ("become a relative of the Buddha") one does not achieve liberation.
Also if one gives his children for monkhood then one becomes related to the Buddha and Sasana. This is considered to accelerate one's goal of becoming enlightened, but this is not a must to get enlightenment.
At a festival for the dedication of the Great Pataliputra monastery called the AΕokΔrΔma as well as the other viharas built by Ashoka, Moggaliputta-Tissa, in answer to a question, informed Ashoka that one becomes a kinsman of the Buddha's religion only by letting one's son or daughter enter the Sangha. Upon this suggestion, Ashoka had both his son Mahinda and daughter Sanghamitta ordained (Mhv.v.191ff.).
Upvote:1
Related in this case does not mean by blood. Rather it is in terms of belief in the shared Buddhist philosophies, or at a minimum maintaining an open mind on the subject. Someone not related has no interest in attaining liberation, and such a person cannot be forced or coerced. Thus, they cannot be helped.