As Monarch cannot behave like a spreadsheet and compare or otherwise access values from one row to another, we're left with devising other means to prepare this type of activity.
I'd develop a simple list in Excel of all of the invoice numbers that you want to review, and then, using Monarch, I'd export a list of invoice numbers found in your report.
Now open the Excel list as database source, and prepare an external lookup to the exported invoice numbers, importing ReportInvoiceNumber. Where ReportInvoiceNumber is null, it wasn't found in your report.
Now you can use a calculated field to build a message:
It likely shouldn't take more than a couple of minutes to prepare.
What is the source of the data? The only way I could see it happening in Monarch is via a report, use a memo field and compare values within the field. However, if this was to continue indefinitely, ie. row 1 to 2, row 2 to 3, then it would most likely not work.
As Data said, it will end up being a multi-model design.