Firstly, you can only use money from an HSA to pay for expenses that were incurred after the HSA was opened. As long as the HSA was opened before the $14K bill (even if it was empty) then you are ok.
Second, don't try and return the HSA money. Instead, report the $866 as a taxable recovery (reimbursement of a previous deduction). Even though you deducted $14K, your tax benefit was only a $866 deduction because of the 7.5% rule. If you get tax-free HSA money to pay the expenses that is more than $866, that would mean you can't have the tax benefit of the deduction any more. So report the HSA as usual (not taxable) and then report the $866 as a taxable recovery. It is included in the very bottom item on the wages and income page under "other uncommon income."
