You are talking about an ancestor narrative report. Your analysis is correct. The only ways to get ancestors for both spouses are to run two reports, one for each spouse, or to introduce a virtual child.
I suppose in the latter case you could save the report to an RTF file and edit it with a word processor to remove the virtual child from the report. Well, there is sort of a third option. You could run two reports, but you could make the two reports be chapters of a book created by RM's Publisher feature. You might or might not consider the Publisher option to be cleaner than using a Word Processor to remove a virtual child. I suspect that you will find that the Publisher option is cleaner and that it is probably your best option.
P.S. Publisher does consolidate any indexes, so that a single index will cover all your chapters. It does not consolidate endnotes. All the endnotes do print at the end of the report, but within the endnotes there is a separate section of endnotes for each chapter.