How immediately MN1 registration for UK born

[easy80]

Hi members

I am basically confused regarding timing for MN1 application for my children who are UK born. My situation is that I have got ILR (Tier 1 general route) from 7-July-2016 and my wife Tier 1 dependent visa. I did not put my children in ILR application because both are born in the UK. The eldest one (4 year old) has traveled to Pakistan and got entry clearance from there, and the youngest (2 year old) has been in the UK since birth.
I have read some threads in which some people are suggesting that a person in a similar situation as mine should apply immediately for MN1 after getting ILR. AndI have also read some threads where it is mentioned that UK born child can not be deemed as illegal if they are not put in the ILR application. But could their status be affected if after ILR of one parent their application (MN1) is not immediately made.
I would be grateful to have some advice as I have not yet applied for my children MN1 due to some financial reasons.

Many Thanks

[vinny]

A person who has leave may become an overstayer when leave expires.
There may be complications if using NHS.
Therefore, should apply for MN1 as quickly as possible.

[easy80]

Many Thanks Vinny for the reply.