ILR for Tier 2 dependent (child)

[Ferronef]

Hi,
I am not sure if my issue requires a new topic and thanks in advance for the kind advises:

I have a situation that I couldn't figure out:

I have a Tier-2 visa. I started working 5 years ago (July 2013) by getting a 3-year visa. I brought my 4-year-old son and his mom (we were not married as we got divorced before) as dependents 4 years ago (a year later).

In August 2016 I have extended my and my son's visa by 3 more years. His mom had left the country a short time before that time and she never came back. We started living on our own with my son.

In September 2017 I got married with my girlfriend and I brought her as my wife with a dependent visa (she has a 5-year PBS dependent visa).

Now, can I include my son's ILR application into my application? The term below is confusing me.

Thanks in advance for any advice.

The requirements to be met by a person seeking indefinite leave to enter the United Kingdom as the child of a parent, parents or a relative present and settled or being admitted for settlement in the United Kingdom are that he:
(i) is seeking leave to enter to accompany or join a parent, parents or a relative in one of the following circumstances:

(f) one parent or a relative is present and settled in the United Kingdom or being admitted on the same occasion for settlement and there are serious and compelling family or other considerations which make exclusion of the child undesirable and suitable arrangements have been made for the child’s care.

[Ferronef]

Is there anyone who can advise ?