Hello @collieculture!
Thank you for your post in the community! After reviewing the FedEx Help Center article, I found that the Multi-Package option is available for FedEx. I've attached the article here for your reference. The Multi Package is listed under the available features for Fed Ex. If you're having trouble getting this to appear as a carrier option, I encourage you to reach out to support@shipstation for further assistance in troubleshooting.
Happy Shipping!
-Cara
