Help with migrating Dataverse instance and merging with another Dataverse installation

[meghan.good...@gmail.com]

Hello!

We're investigating upgrading an old Dataverse installation running 3.6 and merging into an existing 4.8 installation. We're wondering whether there are any known scripts or migration strategies that we should follow as best practice? 

Any advice would be greatly appreciated!

Thanks,

Meghan