This starts with details missing from your initial description. Best guess is that you have a one to many relationship between Donors and Donations though your names for these tables and fields may be different than what I am using:
Donors::__pkDonorID = Donations::_fkDonorID
If so, the report you describe can be set up on a layout based on Donations rather than Donors. You can list the desired fields from Donations in the body of the layout. You can set up a sub summary layout part (When sorted by _fkDonorID) and put fields from Donors in the sub summary layout part so that it serves as a "sub head" for the donations made by that donor. You can even have two such parts, one above and below the group of donation records. If you define a summary field in Donations for computing the total donation amounts, you can place this summary field inside such a sub summary part to show the total donations made by a single Donor.
And it's possible to get a report where there is a single row with the donor's info and a total instead of a list of the individual donations.
To get a report for a specific group of donors, you would normally perform a find on this report layout specifying the criteria that you need in order to find the donations made by those donors. This can be a manual find, but often it is scripted. Either way, you'll need to sort the found set of records by _fkDonorID in order to properly group them by Donor or the sub summary layout parts will not be visible. ( Would sort first by DonorID and then by Donor name to get an alphabetized list of donors in such a report.)
Here's a thread with a lot of scripted find examples that you may find helpful: Scripted Find Examples
And here's a tutorial on creating these kinds of summary reports: Creating Filemaker Pro summary reports--Tutorial
For an explanation of the relationship notation that I am using, see the first post of: Common Forum Relationship and Field Notations Explained
Just what I needed. Thank you.