I don't know.. Then adopt boys and if they are infants, the mother can feed them so the boy would become a mahram, or else take some pills to induce milk and then put a spoon full of breast milk in the cereal milk or something.. There should be ways around it.. The amount of orphans in this world is shameful. Anyhow, maybe single woman parents?
For some reason I feel that adopted orphans SHOULD become mahrams.. Maybe they can't.. But, one would think that Allah
would prefer that these kids be adopted and integrated than grow up without families, love and a chance in this world.. Nevermind they dawah they would receive.
Sometimes I can't wrap my head around it, but Allah knows best.