Okay so I tried this yesterday. But you need to get an award ticket on partner first, then add AS leg. Can't do it the reverse way (book AS leg first then adding partner award). Basically you need to find routing with lowest price (T class) then call AS reservation tell them the dates routes and specific flight numbers. Then they will ask your credit card info to charge $5.60 tax. But AS told me you can't add overnight connection cuz AS consider domestic connection as 4hrs max, anything beyond that they consider it as a stopover. So instead of ADK-ANC (overnight)-SEA-ONT they could only tag FAI-SEA-LAX (same day short connection) to my LAX-DOH-BLR QR award booking.. but hey I will take it, 3 trips in one!