Missing Surname field in your passport? Here is my detailed experience of getting this problem fixed...

Some context:

 I was planning to apply for a popular exam, and was required to enter my Given Name and Surname in the registration site. That's when I opened my Passport (PP) [was going to use PP as the identity proof] and realized that my Surname field in the PP was blank, and my surname was nonchalantly sitting in the Given name section along with my first name and middle initials expanded. Did a little bit of research and came to know that empty surname field in PP had many negative implications when going abroad. So, I decided to get this problem fixed! this was done in September, 2013.

Given Name: XXX YYY ZZZ
Surname: "blank"

or

Given Name: XXX ZZZ
Surname: "blank"

want as

Given Name: XXX YYY
Surname: ZZZ

or

Given Name: XXX
Surname: ZZZ

Remember this blog may help you only if you have your Surname/Last name printed in the Given Name section, or for South Indians [Who have their father's name as last name]. If you want to add a Surname because it was completely missed out [even in Given Name] then additional documents may be required [Process remains same].

Since my appointment was at Bangalore, Lalbagh PSK I can only detail the procedure there. It should be similar in other PSK's as well. Also, I booked in Tatkal slot.

Process:

Step 1: Register

• Go to the PP website [http://passportindia.gov.in/AppOnlineProject/welcomeLink] 
• Register as a user

Step 2: Submit Form and take appointment

• Login to the PP Website, select the "Apply for Fresh PP/reissue of PP"
• Either Download the interactive PDF, fill it offline generate xml and then upload it to the website or fill the form online.
• While entering details in the form choose the "Other" option as reason for change. In the text box generated, enter "Name Bifurcation".
• If you are retaining the previously entered Present Address, No additional address proof document is required. If not, then make sure you have address proof for the new address. 
• Once you have submitted your form, Go to the View Saved/Submitted form option on the Left corner of screen.
• Select the respective ARN, and click Schedule Appointment. [Note: you are expected to pay partial amount  of the reissue of Passport fees online while booking your appointment, details/options are specified in the website as you proceed]
• If no appointments are available for booking on that day, the system will give you a Date and Time, when you can come back and book an appointment. Try booking on a High Speed Data connected system for successful appointment booking.
• After scheduling an appointment print the Application receipt. It will detail your appointment time, date and place and Batch Number.

Step 3: Documents Needed:

• Your old passport copy, with first two and last two pages. Self attested.
• Your old passport [they need to stamp cancelled on it]
• Application receipt. [print from the system]

May or may not ask - Annexure E, Address Proof [Did not ask for me :)]
Use the Document Advisor tab on the left menu to identify what documents are needed.

Step 4: Passport Seva Kendra (PSK)

• Show up at the PSK before the given time. The guards will direct you to a Token Giving area.
• There will be a separate line for Tatkal appointments. They will ask for your Application receipt, and other documents and your Old passport.
• They will inform you to wait for a while [I had to wait for 30 minutes].
• Then they will call your name and hand over a file to you with your Application receipt, Documents and Old PP. They will also give you a token number.
• After this you can enter the area with counters A B and C.
• Counter A: will take your picture, finger prints and signature. They will also collect the remainder of cash we need to pay, and give you a bill receipt.
• Counter B: Govt official will review your documents and ask for the reason of change [say name bifurcation]
• Counter C: Govt official will review your documents again, stamp cancelled on your old PP
• Next go to the Exit counter, show your bill receipt. they will scan it and give you an acknowledgment sheet.
• You are DONE !!! [From Counter A to Exit Counter it took me only 5 minutes -- may be because I booked it in Tatkal]