Children, Avatars, and Bond units all have an extra section added to their character block. For Avatars and Bond Units, this section contains character creation data. For children, this contains parent information. I haven't tried it yet, but it will likely cause issues if a unit missing the child block is converted into a child. I know it causes issues for a Bond Unit or Avatar to be missing that block. Doesn't make the unit illegal online, the only issues I've seen are appearance based. Where you playing on casual when these kids died?