Dataverse : Multi-Table lookups
Dataverse : Multi-Table lookups or Polymorphic lookups is a GREAT feature that all of us are waiting since years ! Let's take a look on how to configure it and how it works.

When working with CRM Package Deployer, it always does an "Upgrade" process while importing a new solution. Please check out this post to find out more about the different solution update processes:
https://dynamics-chronicles.com/article/alm-and-dynamics-365-solutions-explanation