Tier 2 Dependent visa extension fund Maintenance

[mannai]

Hi,

I am having ILR and my family (wife and son) tier 2 visa is getting expired this Feb 2020. They are eligible to get ILR coming May 2020. I am in the process of extending their visa. But I just realized I haven't maintained the fund in my bank account for the last 90 days.

I have the following options to show for fund maintenance.

1. Can I show my Ltd company bank account and letter from my auditor since I and my wife are the only directors of the Ltd company? I have enough fund in the company bank account

2. I have an account in NS&I premium bonds and having some bonds(value 6k) for more than 6 months. Can I show the transactions of these bonds as proof for fund maintenance?

3. In my bank account, the fund(around 2k) maintenance was ok until Dec 15th, after that for 10 days the fund went down to very low(£100) by mistake and currently, the balance is more than 3k. But during these 10 days of time, my wife's bank balance is 1.8k. Can I show both my and my wife accounts as proof for fund maintenance?. My wife bank balance is ok only after the end of November(less than 90 days)

4. Can I request a letter from my last sponsor(thro I got Tier 2 General visa) to support fund maintenance?

It will be a great help if someone suggests a suitable option to go for my Dependent visa extension.

Thanks
Mannai