Is it permissible to shorten a baby girl's hair to exit the state of Ihram, and is the Umrah performed on behalf of a baby girl, for whom the mother made the intention for Tawaf and Sa'i, valid?

The Umrah of a boy and a girl is valid. The guardian must ensure they avoid the prohibitions of Ihram, perform Tawaf and Sa'i with them, and shave or shorten their hair from the entire head. It is permissible for the guardian to perform Tawaf and Sa'i with the carried child with a single intention for both himself and the child, and this is sufficient and valid.