...in the same way you're not allowed to share an Oyster with a period
Travelcard on it....

Another question I can't answer to my satisfaction on tfl's site: Is a
Travelcard loaded onto an Oyster the same thing as a traditional paper
travelcard? eg: it can be programmed to be effective 1, 3, 4 or 7 days?
If so, maybe that would solve my dilemma (or exacerbate it!).

Rich