i have attached one boot lun in my server with multipath (4 paths), during installation installed SLES 12 sp1 on single path (/dev/sda), now i am trying to enable multipath on existing root file system, anybody has idea how to do it?

Four paths:
/dev/sda (OS installed)
/dev/sdb
/dev/sdc
/dev/sdd

Thanks
Mahesh