// copy original formula but adjust 3D refs to the new external sheet index
int newExtSheetIx = workbook.checkExternSheet(newSheetIndex);
Ptg[] ptgs = origNameRecord.getNameDefinition();
for (int i=0; i< ptgs.length; i++) {
Ptg ptg = ptgs[i];
ptg = ptg.copy();
if (ptg instanceof Area3DPtg) {
Area3DPtg a3p = (Area3DPtg) ptg;
a3p.setExternSheetIndex(newExtSheetIx);
} else if (ptg instanceof Ref3DPtg) {