I discussed this with Jack. His advice is below:
It is doable as a single transaction under Regulation Z. The big question is will your LOS handle it and how will you input the numbers to get proper disclosures out of the LOS. None of the sample forms include a purchase/refi combo, so we and your LOS have to make a common sense best guess. Our guess won’t work if your LOS can’t match it. We suggest you check with your LOS vendor. If you decide to do it manually then we can help.