Forward Contract - Partial Utilization

Dear All,

We have a scenario where we have to make partial utilization of forward contract.

Eg:

On 01.12.2012 a forward cover is booked for USD 100000 @ 50 with maturity date on 1^st May 2013.

On 02.02.2013, say USD 20000 @ 51 is utilized for paying off a loan.

Further, we have to record the utilization charges as well.

Should we have to make a roll over for USD 80000 (balance value in contract)? If yes, then can you explain what will be the process?

If Rollover, then should we change the Netting transaction (103) amount to USD 20000 and Roll over (104) to USD 80000 with the same maturity date?

In case there are few more utilizations before the maturity date then should the above process be repeated?

How to account for the gain or loss from the utilized portion?

Thanks,

Kamal P