Can a person make the intention for Umrah and perform the rituals on behalf of himself and his minor daughters (6 and 9 years old) at the same time?

It is permissible for a father to enter into ihram for Umrah on behalf of himself and his daughters. As for the discerning child (male or female), they have their own specific ihram, and representation is not permissible for them in this regard. However, the guardian's representation for them is valid in matters they are unable to perform. As for the non-discerning child (male or female), their guardian enters them into ihram by intending to include them in the Umrah.