Further leave to remain -dependent children

Hello everyone.
I returned to the UK from Vietnam with 2 dependent step daughters on my wife's spouse visa. When we applied my second daughter was under 18. But that was during Covid and it took 1 year for them to approve the visa. Then more time to settle things up in Vietnam and get here. So by the time we got here after the LLR spouse visa was granted daughter 2 was over 18. Soon we must apply for FLR (part 2 of the spouse visa) and my wife has read the following on the gov.uk website (apparently).
Applying for FLR with dependent children
You can add children to your application if both of the following apply:-
1. They are under 18 or were under 18 when they were first granted leave.
2.They do not live an independent life.
But I said-you can be under 18 when you first apply-it wasn't our fault that Covid struck. Also I don't believe they would grant LLR (part 1) then not allow part 2 when she's been here 2,5 years already. Or break up a family and send her home -that statement MUST be wrong.
If you know anything about this please let me know so I can stop my wife worrying. I just said I don't believe it. The gov. wouldn't do that, that would be like saying yes we granted LLR but only on the condition that you will never get part 2 for her.
Kind regards,
Darryn

Do they still live at home? If yes how dependent on you and their mother are they? Just because they are over 18 dies not mean they are independent. Do you and mum pay for their daily living, clothes, mobile, Netflix etc? Just show how they are dependent they are on you. Should be alright but wait for experienced moderators to give their 2 cents.