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Thanks for your enquiry.
If the property is in the sole name of his new wife, I'm afraid it is not legally possible to register a Charge against it.
This is because a Charge can only be placed on a Property if that property is legally owned by the debtor (your ex husband). Te fact that it is the "marital home" is irrelevant I'm sorry to say.
I am sorry this is not the answer you were looking for, but if I hope I have answered your question.
Can I assist you any further?