Poshmark now has the ability to issue partial refunds for orders that have issues upon delivery. Please see the Poshmark help page for the latest information: https://support.poshmark.com/s/article/return-case-US?language=en_US
However, due to nuances within this capability, sellers still should not send incomplete orders, but rather cancel the entire order if they are unable to fulfill it entirely.
Should you mistakenly ship a partial bundle order, this will likely generate a Canceled but Shipped order, requiring Poshmark support intervention. Please reach out to our Enterprise Orders team for assistance on how best to handle.