Sam Decker writes about piggybacking:
The idea of piggybacking is to look at any marketing program and piggyback on it with another marketing message. Or, alternatively, piggyback every marketing vehicle to reinforce your main message (example: logos on delivery vehicles, URLs on receipts, etc.).Marketers walk a fine line between piggybacking and turning customers or diluting messages. I like the way Decker recommends reinforcing your main message with piggybacking.