First spouse visa - how to prove income + cash savings?

[777GE90]

Hello, I am helping my sister submit her first spouse visa application but unlike mine she is below the financial requirement. She currently earns £25,396.80 per annum PAYE / permanent full time contract and I have therefore calculated she needs an additional £25,008 in her bank account for at least 6 months to bridge the gap for the minimum £29,000 financial requirement.

I understand she can prove the financial requirement by doing a combination of Category A + Category D, but please correct me if I am wrong.

However, I would appreciate if one of you legends can confirm that I am not missing any required evidence to prove this. Here is what I got lined up:
- She will get a letter from her employer with 12 months payslips, showing she earns that level of money for at least 6 months (she got a payrise to her current salary on 1 April 2025 so hasn't earned that level for entire 12 months but the application is asking for 12 months payslips regardless).
-12 months bank statements.
- She will have funds in excess of the £25,008 for over 6 months in her bank account, solely in her name. As part of this she transferred a lumpsum of cash from another bank account which she holds jointly with her parents to her bank account.
- Should she provide a statement from the joint bank account in the month she transferred the money or is this not required?
- We will provide a letter confirming the source of funds, which she will declare funds to be purely through her savings from employment income, some of which she previously held in the joint account with parents but has now transferred to her sole account.
- She has been working for over 15 years, I will provide the last 2x P60 documents, does she need anymore proof?

Does she need anything else?

[777GE90]

Another complication we have is that her workplace only seem to have access to the last 9 payslips and we are struggling to get them to come up with the remaining to get us 12 months.

Since she is doing Category A (i.e. she has earnt the same salary, below the threshold for over 6 months - she has been employed for 3 years+ with this employer) and combining with Category D, am I right in thinking that only 6 months payslips are actually required? The application form seems to wrongly ask us for 12 months payslips anyway?