Hi Shahida,
You should be fine with passing custom link (s.tl) server call on each step or blur condition as these calls are required by Adobe only to record all these instances to determine abandoned for each form field. You will not use instances for reporting instead will create a visitor based fallout visualization which will show you abandonment by visit or visitor. for more details refer to the reporting section in my previous reply.
Ex.
user 1 lands on registration page > enter user name > confirm user name > enter user name > enter passowrd > exit.
user 2 lands on registration page > enter user name > confirm user name > enter passowrd > confirm password > exit.
user 3 lands on registration page > enter user name > confirm user name > enter user name > enter passowrd > confirm password > > enter DOB > exit.
user 4 lands on registration page > enter user name > confirm user name > enter user name > enter passowrd > confirm password > > enter DOB > form submit.
You rules should set below everytime user interact with form field:
set custome link name "form:registration-un" for fields-Username,
set custom link name "form:registration-cun" for Confirm Username,
set custom link name "form:registration-pw" for Password,
set custom link name "form:registration-cpw" for confirm Password,
set custom link name "form:registration-dob" for Date of Birth.
set custom link name "form:registration-submit" on final form submission.
Cutom link Name ( Form Steps)
| Visitor
| continue %
| Exit %
| Custom link instances (will not create a report on this just FYI!) (only used to derive abandonment)
|
---|
form:registration-un | 4 | 100 | 0 | 7 |
form:registration-cun | 4 | 100 | 0 | 4 |
form:registration-pw | 4 | 100 | 0 | 4 |
form:registration-cpw | 3 | 75 | 25 | 3 |
form:registration-dob | 2 | 50 | 50 | 2 |
form:registration-submit | 1 | 25 | 75 | 1 |
Example Snapshot.

Thanks,
Asheesh