If they were taken away they were culled from the game and there is no way to get them back. I have heard that there is a mod that instead of them being culled they get put up for adoption. You may want to look into that for any future events like this.
Yes, there are settings within MCCC that will allow another family to adopt the baby/child should it be taken away within game. If you deleted them manually, then there is no way to get them back, unless you have an earlier save and can upload them to your library or gallery and redownload them into your current save. Like @jpkarlsen said, once they are culled, there is no getting them back (in that save). Hope this helps!
