2. You'll need to supply letters addressed in joint names, for example joint bank account statements, utility bills, council tax bill. I think the official line is to supply 8 letters spread over the duration of her time spent living together.
If you can't supply the full amount in joint names (we couldn't) then you have to supply additional letters addressed to you both individually. For my wife I included things such as her NHS letters, the letter sent to her confirming her NI number, employment letters such as wage slips and P60, anything official, things like that.
I also included other items such as our sons birth certificate showing us both named as parents.
As for more tests, probably by the time your wife has to apply
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