how we can assign the already created interval number to group in EHP6

Dear PM Guru's

Currently we are using ECC6.0, EHP 6 with patch level 0002. In that when i am trying to assign the external interval number range to other groups. How i can assign that interval number range to other group, i could not find the assignment of interval number range option in EHP6. Please let me know if any other process is there to update the or to assign the interval number to other groups.

regards

JKM