Ok. I understand now.
If this is the case: You want to varyonvg from one Machine/Server at a time then there is no need for enhanced concurrent mode. You can use SHared Volume Groups / Logical Volumes.

Anyway, let us move to solve your issue.

1) yes you can use always the CHDEV command to give the PVID's to the HDISKs
on HAG

2) OR the other best way is to use smitty importvg on HAG but since you don't know the PVIDs then you don't know which disk is with which VG ?

if you know how to check the LUN ID in AIX and check in the storage then you can proceed with step 2
here is how

HOST: AKI
hdisk2 000b80bf27ceb498 vg00 active
hdisk3 000b80bf6c9b41f8 vg01 active
hdisk4 000b80bf6c9a3a8d vg02 active
hdisk5 000b80bffbb9f2af vg03 active
hdisk6 000b80bffbb6bf7b vg04 active
hdisk7 000b80bf27dc7320 vg05 active

HOST: HAG
hdisk2 none None
hdisk3 none None
hdisk4 none None
hdisk5 none None
hdisk6 none None
hdisk7 none None

Objective: We want to know {{ AKI :: hdisk2 000b80bf27ceb498 vg00 }} is what on HAG ?
Since you don't have the PVID on HAG, so it could be HDISK2, HDISK3, ........, HDISK7

a) Check the LUN ID on AKI for HDISK2
lscfg -vl hdisk2

check for location --> LXX <-- This is in HEX
or
lsattr -El hdisk2
search for LUN ID :: 0x2C000000 <-- this is in HEX
convert this HEX to decimal and on HAG search for this LUN ID (hdisk2,hdisk3...hdisk7)

OR easier method
just give it PVID on HAG
chdev -l hdiskXX -a pv=yes
chdev -l hdisk2 -a pv=yes

see if the PVID is same or NOT ?

3) So, if HAG HDISK2 has same PVID=000b80bf27ceb498 as AKI HDISK2
then you know HDISK2 on HAG has Volume Group : vg00

4) Find out the major Number (recommended practice)
on AKI go to
cd /dev
ls -ltr | grep vg00
ls -ltr | grep hdisk2
check for major number which will be like 42,0 hdisk2 or vgname (don't remember exactly)

5) on HAG run this command
smitty importvg
VG NAME: vg00
Physical DISK: hdisk2
Major Number: whatever we found on AKI for vg00 / hdisk2

hope this helps... if not post here.