Do you open up a new report for each month, listing the donations received that month? Is that the 50 reports?
If so, I assume that the names may be the same for several of the reports? Many may be new donations or one time individuals?
Again if so, you need to have a single report listing every person (company) makes a donation.
In each of the 50 reports you would Total To the single report, where a duplicate account for each individual (company) would be listed. Then you will be able to get the info needed.
You can use BLKCOPY & BLKPASTE, to copy each of the 50 report accounts in the Single report. Then use SORTREPT, to organize by Name or Description (hopefully you’ve used a similar name or the same description where the person is the same. Then delete the duplicates.