term used in marketing/advertising

here a reference to confirm the use of joint in this context:

July 11, 2001 | InternetNews - Advertising Report Archives NFL Inks Ad Deals ... The
deal also includes joint online-offline promotions through non-Web ...
www.internetnews.com/IAR/article/0,,12_799531,00.html - 27k

I think it's the usual term in merchandising offers.

Just a suggestion:

magazine + internet package deal offer

The concept of "piggybacking" is one of dual function.

French:Advertising Media
couplage-groupage s MASC

English:Advertising Media
piggybacking s

1985-09-12

This related term from Barron's Dictionary of Marketing Terms

piggyback commercial
two or more broadcast commercials aired one after the other, featuring different products of the same sponsor. advertisers use piggyback commercials to get two or more unrelated advertising messages into the time allocated for one, without increasing commercial time. Advertisers generally purchase commercial spots from stations and network as a single unit.

There is also the piggyback label (pressure-sensitive label)
label with a gummed adhesive backing that can be peeled off the backing material and applies permanently to another surface simply by pressing [...] Pressure-sensitive labels are sometimes included in direct-mail packages to perform the dual function of addressing the package through a window envelope and enabling the recipeint to peel off the label and apply it to an order form (also called piggyback label), making it easier for the recipient to complete the order form and increasing the likelihood of response.