I'm currently helping my wife apply for an extension to her spouse visa.
We used an advisor for her initial visa just to be extra safe, this time we thought we'd do it on our own to save on costs, and... the whole thing is surprisingly confusing

A few questions on the application form stumped us - could someone please offer advice on how to answer them properly?
- "What is the start date of your current visa or leave to remain?"
Her initial spouse BRP was issued in March 2020, then a new one was issued in December 2020 after she had changed her surname. Both BRPs have the same expiry, so technically this was not an extension, just a reportable change in circumstances. Would December 2020 be a correct response in this case?
- "Time lived in the UK" and "Have you been out of the UK since you started living here?"
My wife initially stayed in the UK on a YMS visa, should we include this time or only indicate the time she lived here on a spouse visa? If we include time spent on a YMS visa, should we again indicate absences during that time period (they were all reported when changing to a spouse visa), or only the absences after her initial spouse visa was granted?
- "How did you enter the UK?"
In our previous application, there was a question "Did you enter the UK legally?", then asking if she is "on Temporary Admission, Temporary Release or Immigration bail". In the application form we're filling in now, there's no initial "did you enter legally" question, and the only options in "How did you enter?" are "Granted temporary admission/bail", "entered illegally" or "other". This seems a bit strange, is this normal? For now I've selected "other" and explained that she initially stayed here on a YMS visa, then changed it to a spouse one, providing all past BRP numbers.
- "Is this the first time you have applied for a partner route, or an extension, with your current partner (including as a fiancé(e) or proposed civil partner)?"
The wording is a bit unclear - I'm assuming this is a "yes" as we never applied for an extension before?
Also, I know that we can use my wife's previous English exam certificate to apply for an extension, does anyone know if we're able to use our previous marriage certificate copy to apply this time? I have an original certified copy dated December 2019 that we also used in our previous application, it would be great if we could just submit it again, but is it the case that they'd need something newer than that?
Thank you all so much - hopefully my experience with this application will lead to some experience that can help others in the future.