Note that, whatever you use them for, tandem series have all the flexibility of original series. Each has its own scoring system and its own table of discards, both of which could be different from the original series from which they derive results.
To make a tandem series, open the real series for editing in the schedule menu. Click the button to make a tandem series, choose the class for the tandem series and give it a name. The new tandem series will draw its results from all the races in the real series, but will use the handicaps and boats in the tandem class.
If you do not want all the races in the real series to feature in the tandem series, you edit the tandem series and remove any races you do not want. Note that if you add races to the real series after setting up the tandem series, they are not copied to any tandem series automatically. You need to edit the tandem series and add the extra races.
Note that a tandem series cannot draw its races from more than one real series, although it can contain a subset of the races in a real series. If you need to make a set of results from a long series and for smaller subsets of that series, such as a season-long series divided into spring, summer and autumn subseries, you need to make the long series your real one and use tandem series to select the spring, summer and autumn subseries.