Although Mo Wu divorced Mo Yongfu and couldn't take her four children with her, it wouldn't be difficult for the children to break away from the Mo family and start their own household if they were willing.
However, this "breaking away" came with a premise: the four siblings, led by Tie Tou, must not bear the stigma of unfilial conduct or the villagers' disdain as they left Lao Mo's House!
Even though Lao Mo's House had long lost its good name, and everyone in the village despised them, Old Man Mo, Mrs. Hong, and Mo Yongfu were indeed the direct elders of the four siblings. If they dared to abandon their grandparents and father, even if the villagers didn't side with Lao Mo's House, they would certainly gossip about the siblings' unfilial behavior. They would never be able to hold their heads up high in the village for the rest of their lives. Furthermore, they might not be accepted by the villagers, who would think that they could corrupt the ethos of Liu Yang Village.