QUOTE(NickD @ Jun 2 2008, 01:40 PM)

From the instructions
"Part 9. Information About Your Children.
A. Write the total number of sons and daughters you have had. Count all of your children, regardless of whether they are:
1. Alive, missing, or dead;
2. Born in other countries or in the United States;
3. Under 18 years old or adults;
4. Married or unmarried;
5. Living with you or elsewhere;
6. Stepsons or stepdaughters or legally adopted; or
7. Born when you were not married.
B. Write information about all your sons and daughters. In the last column (''Location''), write:
1. "With me" - if the son or daughter is currently living with you;
2. The street address and state or country where the son or daughter lives - if the son or daughter is not currently living with you; or
3. "Missing" or "dead" - if that son or daughter is missing or dead.
If you need space to list information about additional sons and daughters, attach a separate sheet of paper."
And From the form N-400
"Part 9. Information about your children.
A. How many sons and daughters have you had? For more information on which sons and
daughters you should include and how to complete this section, see the Instructions.
B. Provide the following information about all of your sons and daughters. If you need more space, use a separate sheet(s) of paper."
Now I hope that we filled out the N-400 correctly, I, as the US citizen was never asked anywhere on any form about my own children, but they are over 18 and gone. I took Part 9 as being the children of the applicant that would be my alien wife in previous forms and those we listed all of them like the form says to. But in your case as the applicant the instructions state to list "6. Stepsons or stepdaughters or legally adopted" and as the children of your US wife are your step children, you have to list them.
Since I am the spouse on my wife's application, they did ask plenty of questions about me, but never about my children. And I took it that my wife was never legally responsible for my grown children, and they asked the names of her children with all the conditions listed above, and not about her spouses, (me) children. But in your case, you are legally responsible for your wife's children just as I was legally responsible for my wife's children. So you have to list your wife's children.
In my case, if I screwed up by not listing my children, so be it, but they are not living with us nor is my wife legally responsible for them. If they asked to list the all children of the US citizen spouse, that would be different, but they didn't, I would use this as an argument.
This is not the only part of the N-400 that is confusing. I did look at the old INS form, was written in English so you could understand it.
Thanks everyone for replies.I have'nt lsited childeren on I-485 but at the interview officer asked me.I thought officer is just asking date of birth and name of childers for interview purpose only.I did'nt include on I-751 because non of our childeren needs Immigration they are born citizens,Idid'nt want to confuse Immigration.Now again they are asking for childeren,If non of the childeren need Immigration benefits are you sure they need to be added.
I have'nt included kids in any of immigration forms before If I 'll include now It may Confuse them.