I just did large open jaw IND-SFO return BWI-IND on CO. Also have done IND-LGA return EWR-SFO on DL. UA and NW would not allow either of these (jaw too wide) while CO, AA and DL had no problem. UA and NW do allow some open jaws and I have done IND-SFO return LAS-IND. Do not know about US. Good luck.