*** First and foremost, apologies

I am a PBS dependant visa holder (my spouse is a Tier 2 / Skilled Worker visa holder) seeking to rightfully extend my visa and my stay. I am confused

1) https://www.gov.uk/skilled-worker-visa/ ... d-children
OR
2) https://www.gov.uk/skilled-worker-visa/extend-your-visa
If I try to use Option 1, it says I can't apply from within the UK (which leads me to believe that it is the wrong link).
If I use Option 2 (which I think is the correct link, it asks me for a Certificate of Sponsorship (CoS) reference number. I don't have a CoS number since I am a PBS dependant as stated above.
a) Is it my spouse's employer CoS that I need to provide?
b) If yes, is there any additional information I need to provide to establish that it is indeed my spouse's CoS OR alternatively do I have to establish that my spouse's employer has sponsored her using that CoS?
The reason I raise Pt a. and Pt b. is that currently my spouse is on Tier 2 visa sponsored by her 3rd employer/sponsor; whereas my dependant visa was issued by her 1st employer/sponsor.
Appreciate your response, advice and suggestions!
