Trying to book multistop business for wife and I Chicago via Frankfurt to Cairo and back via Montreal, since for end of May it is a good deal (less than premium economy) but when I go to pay I do not have the option of Money and Miles. Yes, I understand this might not be the best use of points but sitting on 140,000 and thought this might be a good way to bring the $ amount down.

Tried a dummy booking economy Chicago to San Fran and it showed up. Tried to read the rules and I don't see anything about restrictions. Would calling do anything?