Go to Version Sync in Project A (Classic: Project A > Project settings > Version Sync/ Next-gen: Project A > Project Settings > Apps > Version Sync)
Create new group “PA” with default settings
Go to Version Sync in Project B (Classic: Project B > Project settings > Version Sync/ Next-gen: Project B > Project Settings > Apps > Version Sync)
Select the group “PA”
Select the desired outcome for synchronization
Save
If applicable sync existing versions from Project B manually
Future version will be synced automatically.