how do i file a claim on behalf of a creditor

[wrenegade]

I am a pro se Ch. 13 filer whose plan was confired in January. My plan pays back 100 percent to all creditors.
The last day to file claims was March 18 and a finance company that I owe approx. $15K did not file a claim.
That finance company has my car title as security, although the finance company loan was not used to purchase the car.
I crammed down the value of the car to $4500 in my Ch. 13 plan.
I understand secured loans survive bankruptcies, and the finance company could come after my car post-discharge if they don't get paid through the trustee.
I'm wondering if I should file a claim on behalf of the finance company for the secured amount. Do I just use the same form the creditors use to do this? Would the court's confirmation of the cram-down be evidence of the secured loan?
Also, can I file a claim just for the secured part of the loan, leaving the remaining $10K or so unpaid? Or do I have to file a claim for both the secured and unsecured amounts.

[oops123]

I see no reason you need to file a claim on their behalf. If they don't "fight" the decision of the plan, and its confirmed by the court, they get what they get and cannot take the car. That is my understanding of how it works, others should be along to correct me if I am wrong.