You can specify specific disks by using the prediskname and secdiskname parameters (for both the primary and secondary sites).
# vradmin help resizevol
VxVM VVR vradmin INFO V-5-52-0
Usage: vradmin [-g diskgroup] [-f] resizevol rvg volume length [pridiskname=primary-disk-names] [secdiskname=secondary-disk-names]
# vradmin help resizesrl
VxVM VVR vradmin INFO V-5-52-0
Usage: vradmin [-g diskgroup] [-f] resizesrl rvg length [pridiskname=primary-disk-names] [secdiskname=secondary-disk-names]
Example:
# vradmin -g vvrdg resizevol rvg vvrvol01 2g pridiskname=disk1,disk2 secdiskname=disk1,disk2
# vradmin -g vvrdg resizesrl rvg 2g pridiskname=disk1,disk2 secdiskname=disk1,disk2