Hi arshad,
it could be anybody's account, no matter who it is.
i kind of played with it, my wife has one gc key, and me have 1.
1 went to her account, linked it, came back to my account linked it, it automatically was removed from my wifes account saying linked to other account and finally linked it back to her account.
the simplest way i found to link is
select permanent residence>family class spouse> select application no. and last name>
insert her file no. with capital F
make sure you fill same dob, last name as in original app
now city of birth press space once, country select India if India
select province and city to land as same in app
and married and no. of applicants as 2 if no children, and add 1 for each child, i mean you have to count yourself too.
It shall definitely work.
Good Luck