Can a bunch of people be Yotzei their Chiyuv of Shalach Manos with one Basket? What are the Halachic requirements for doing so?
A Sephardi approach here from Reb Ovdiah Yosef where he allows it.
May two or more people send jointly?
Yes, but the package should contain the correct quantity for each of the senders.
See there for some other caveats and conditions.