Children on visit visa applied for registration

Dear All
My children are on visit visa here and we have applied for their registration under section 1(3)
as you all know they are taking very long. What should I do if the certificates don't come within the visa period should we leave UK or its ok cause they will be british citizens after getting certificates. Pe
lease help
Thanks

Were they born in the UK?

yes and I am on ILR
Thanks

There should be no issue, they are entitled to register.

Thanks very much
does passport office check the visa status cause we will have to send the current passports with the application forms
Thanks

No, because when you apply for their passports, they will already be British.

Thanks very much dear CR001 for your help