Not necessarily so. The most successful fostering of chicks to a broody happen when the broody has been setting for at least a couple of weeks, and when the chicks are still within the 2 day window of imprinting. The chicks must imprint to the hen, and the hen must imprint to the chicks. Some hens are very accepting of fostered chicks, and some are not. Some broody hens are very good at incubating but freak out and abandon the nest, or even kill the chicks once they start pipping. It all depends on the hen and the circumstances. When dealing with living animals, there is no one set answer.
To OP: How long had the hens been broody (sitting on the nests day and night?) How old were the chicks?