Yes, you need to use Single-Item vendors. This is in an effort to help reduce lag across the event. Multi-Item vendors are typically a part of a network and when you have a lot of them in 1 region, it tends to slow down the servers. In an effort to alleviate this, we are allowing merchants to use an unlimited amount of ACS SciFi Expo vendors (up to package vendor limit), which includes options for both 100% donations, and 50% split donations.