Does the girl become the daughter of my relative by رضاعة (nursing), and thus a sister to her male children, if I nurse her, knowing that her youngest child is approximately 10 years old?

If a girl is nursed by a woman five known sucklings within the first two years (of the child's life), the woman becomes her mother through suckling, and the girl becomes a sister to the children of this woman through suckling. Women's milk establishes prohibition in all cases. So, if milk flows without pregnancy, it still spreads prohibition.