Additional person in baptismal font?

We have a girl who is preparing for baptism that probably does not require baptism, but her parents would like her baptized.

Because of the situation, there is concern that she might become super agitated with a missionary or other adult baptizing her. There is a suggestion that possibly her father could be in the font with the girl and the baptizer to help keep her calm. Her father is a member, but hold no priesthood and will not be baptizing her.

Is this allowable?

I'm not seeing anything in General Handbook 18.7.7 that would prevent that.

Leadership should review General Handbook 38.2.8.1 "Persons with Intellectual Disabilities" as well as 38.2.5, which ends with "If leaders have questions they cannot resolve, the stake president contacts the Office of the First Presidency."

This is really not a tech question, but since it has been posted I would add that making a person who may be not accountable then accountable by baptism opens up other questions regarding temple ordinances.