Declaring my dependents to Home Office

Hi,
I am applying for my visa extension under FLR HRO, I have 4 children 3-5-9-10 who were all born here and the oldest is a British citizen. I have never added the last two kids in my application and they are not in the HO system. I didn't think it was necessary because they did not need to travel anywhere and the cost of obtaining a visa for them was not affordable. I am currently applying for my leave to remain extension and in the form, I am asked if I am responsible for other persons except those I declared. My wife in her own application has already informed the HO that we have just the two kids.
My questions are:
1. Do I maintain the declaration of the two in the HO system or do I add these last two kids to my current application?
2. What are the long term consequences of not declaring that I am their parent on them and myself? eg when they are ripe for their British Citizenship or when I seek further leave to remain?
Please, I would like answers to these questions.
Thanks.