Okaasan's painstaking performance of her role doesn't mean that she will never accept any help. In Family G, Erika found that the okaasan was happy to accept help when she was tired, or when the others were free—on the weekends. However, you should not be fooled—even though the members of this family happily help out, they are merely assistants. This is still a very Japanese okaasan who is still very much in charge of her own sphere of responsibility.
In Devita's case, the okaasan saw Devita as first and foremost a foreigner, even though she was the family's new daughter-in-law. The okaasan proceeded to treat Devita as a guest, indulging her by letting her help, and then repairing the "damage" after she was finished. However, the strain of doing this became too great for the okaasan. Finally, the otoosan had to step in and redefine Devita's position in the family, putting things back into balance and restoring the okaasan to her rightful position as expert in her own sphere of competence. This realigned the relationship between the okaasan and Devita: the okaasan shifted from exhausted host to expert teacher; and Devita is suddenly vaulted from soto guest to uchi daughter-in-law who must learn the ways of her new family so that she will someday be able to take over the role of okaasan.
The okaasan is respected as the central pillar of the family, as someone the family can lean on. Her vital position in the family is a potential source of considerable authority as well as pride.