K4 visa for step children or what?

[bembridge]

My wife recently got her I130 approved. I forgot to file separate applications for her children (9- and 7-year olds) who are my step derivatives. I did not know the step children immigration is not derivative.
Can I apply for K4 visa for my step children after my wife has gotten her immigrant visa or what should I do?
PLEASE ADVISE

[newacct]

No. K4 is for dependents of K3, and K3 is obsolete -- essentially nobody can get K3 visas anymore even if they apply for it.

You need to petition each of your stepchildren with separate I-130s, and they each need to get immigrant visas.