Exicse dealer quaterly return.

Dear All,
We have just started a new firm and registered as 1st stage/2nd Stage dealers under central excise. My query is how to furnish details in excise dealer return. All sales and credit utilized details is quite simple to furnish but real trouble starts with purchase details.
1. If cenvat utilized in more than 1 sales bills then how to furnish in the return.
2. If some part of cenvat of a bill is utilized in one quarter and other part utilized in another quarter then how to furnish details in both returns.
3. If no sales booked against a cenvat bill then how to show in the return or not included in the return.