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It may require a bit more than just evidence of who paid what to be able to claim the interest and taxes when you are not listed on the note or the title. If you made the payments, you may be able to claim a deduction.
The general rule is that you must both own the property and be liable for the note to deduct the interest. The issue that needs to be proved is that you are in fact an equitable owner, that is, that you are the one that enjoys the benefits and burden of ownership. There is a regulation that says the equitable owner (the one with the benefits and burdens of ownership) can take the deductions.
Since the documentation from the mortgage company is only going to be in the other owner name(s) you might receive correspondence from computer matching that does not show you paid the interest; but the rules and regulations do allow for the deduction.
It is not clear why the mortgage is not in your name as an owner (or if you have some documentation, recorded or not of your ownership interest); but you could use an affadavit from the one(s) on the mortgage as to the actual ownership of the property despite the formality of their name being on the mortgage. It should be made clear, by all concerned, just who owns what portion of the property, both now and going forward, as various persons pay various amounts of the cost of ownership.
In tax jargon, substance rules over form. So, if you are indeed the equitable owner then you are entitled to the deductions for amounts that you paid. Of course, it is better and there is less doubt when form follows substance, as well.
I hope this helps with claiming deductions as an owner when the forms do not reflect the facts.