You should post each invoice individually. This will do two things:
- Prove that the goods were purchased as you have a copy of the invoice either stored as a hard copy or uploaded to your accounts program
- Help you reconcile the supplier's statement each month with what you have in the accounts
I know it is tedious when there are so many invoices on the same day, but it is the correct way to do bookkeeping! The effort is worth it if there is an invoice missing too!
I hope this helps!