Set Multiple plant in roles

Dear expert,

I have create role and assigned to user. But a user need multiple plant access to enter MIGO document.

How i can do the multiple plant access to user?

1. Should i create plant wise role?

2. create one role and assign multiple plant.

Actually i have created plant wise role which too time consuming. Please tell me that how can assign multiple plant to a role?

Regards,

PK.