Taking advantage of their sisterly relationship for the first time, the Hallmark Channel and Hallmark Gold Crown retail stores are teaming up on a multimillion-dollar cross-promotional effort for upcoming mini “Stranded.”

Rolling out nationally May 13 — coinciding with the greeting card giant’s Father’s Day sales period — campaign will feature in-store information on “Stranded,” plus details on how to win a trip to Australia.

Mini, debuting on the cabler June 15, is a fresh spin on the classic “Swiss Family Robinson,” with travelers shipwrecked on an island while trying to get from Switzerland to Australia.

In turn, the cabler will drive traffic to Hallmark stores, by running spots plugging the card shops as the only locations to pick up contest entry forms. Local cable operators also will be running “Stranded” advertising.

With 4,500 Hallmark Gold Crown outlets nationwide, Hallmark Channel has the most extensive retail-related marketing outreach of any network, broadcast or cable, according to execs.

“Our independent retailers benefit from the powerful exposure of national cable television programming. The Hallmark Channel benefits by reaching the millions of consumers who visit Hallmark Gold Crown stores across the country,” said Hallmark prexy-CEO Donald J. Hall Jr.

Laura Masse, senior VP of marketing at Hallmark parent Crown Media, added, “This is a natural collaboration. It’s a real win-win for both of us.”

Hallmark stores typically make their promo plans a year in advance. Thus, “Stranded” was the first chance for the stores and the cabler, which launched in August, to work together.