Parallel Sprints

[Mohammad Kettaneh]

Hello,

How can I have "Parallel Sprints"

I have enabled it from (Settings -> Products -> Jira Software configuration -> then enabled Parallel Sprints

In backlog, start sprint is active only for one sprint, please advise 

[Global Tools]

these instance can be made connected using add ons like connect all and then the solution can be obtained to make all issues available and hence searchable.

[Nic Brough -Adaptavist-]

They're separate systems, so you will need to find or write a "federated search" system that can search across multiple systems.  I'm not aware of any add-ons that do that well at the moment.