You have the Customer Administrator or Partition Administrator platform role.
Go to Partition management > Partitions.
Select the checkbox of each partition you want to share.
Select Share.
The Share sidebar displays.
In the Share with drop-down list, select the company with which you want to share the partition.
(Optional) If the company is not in the list, select Related companies to be redirected to the Related companies page. To add a company to the list, see Related companies.
Under Permission, select the permission level you want to grant the target company.