The mother who has a month old chick is not likely to sit on the chicks. Even if she does it is not likely she would slow down enough or stay with them for a full brood time.
Nothing is for sure when dealing with live animals. Although it is rare, some hens kill their own chicks at hatch. Not every broody will accept foster chicks.
@Mrs. K has great advice for how to go about giving a broody hen chicks. Sometimes a hen will take the chicks no matter how you introduce them. Some will only except them when it is done precisely enough that the hen is fooled into thinking she actually hatched them, and a few won't have excepted them even if they did hatch them.
Having a backup to brood chicks on your own is a must.
Nothing is for sure when dealing with live animals. Although it is rare, some hens kill their own chicks at hatch. Not every broody will accept foster chicks.
@Mrs. K has great advice for how to go about giving a broody hen chicks. Sometimes a hen will take the chicks no matter how you introduce them. Some will only except them when it is done precisely enough that the hen is fooled into thinking she actually hatched them, and a few won't have excepted them even if they did hatch them.
Having a backup to brood chicks on your own is a must.