Cross application submission in family court?

[Hullabalooo]

Does anyone know if you have to put in a cross application (form C100) for child arrangements in the family court if you're son's father is already taking you to court for the same thing? I'm being told conflicting things.

No you shouldn't.

And anyway it would be a C2, but save yourself the court fee.

Applicant says: I want arrangement X

Respondent says: I think it should be Y

The court will listen to both parties and decide what is best.