Thank you for your question.
As you are probably aware, child support terminates when your children hit 21 or when they are emancipated.
Ind. Code § 31-16-6-2 provides that a child support order may include sums for the child's education at institutions of higher learning, where appropriate. Since the daughter is under 21, if she is not emancipated, you are merely required to pay child support. If the court order requires college or university, that's another story.
It sounds like the mother is petitioning the court for an order forcing for the payment of college. In that case, if the court may require the father to submit proof of his income. However, for purposes of child support, your income should be irrelevant.
The only way in which you are required to sign the form is if the court requiring as part of the documentation substantiating what each paying parent makes.
Please let me know if you have any questions. Otherwise please hit "ACCEPT", so I may receive credit for my response. Tips and feedback are also appreciated!