Domestic Relations Law 240 governs this issue. The definitional section "Income" provides:
(iv) at the discretion of the court, the court may attribute or impute income from, such other resources as may be available to the parent, including, but not limited to: . . .(D) money, goods, or services provided by relatives and friends. Arguable on the statement of net worth. Given that the statute talks about a finding made the judge, this would suggest a hearing, and of course your fiance's "contributions" being subject to disclosure through her deposition. Having recently litigated such a case in Westchester County much depends on how sharp and how dogged opposing counsel is.