Hi,
You are receiving goods two times a day- The advantage you are using scheduling agreement where you can schedule the delivery with DATE and TIME in t.code:ME38 and based on date with time set- system allow you to delivery for that time but not before that.
But as your process involve multiple deliveries , better go for Evaluated Receipt Settlement(ERS) following process with steps
1. Create contract
2. Create PR from contract
3. Create PO from PR
4. Create goods receipt WRT PO
5. MRRL- Create ERS invoice fro multiple deliveries for PO
6. MR90- Print ERS invoice
7.F-53 or F110 - Vendor Payment
Regards,
Biju K