Apologies for a beginner's question, two actually:
- can Openskies (US-Paris) be included in DONE?
No apology required! Travel on OpenSkies (code EC) is not allowed as it's not part of OW despite being owned by BA. The fare rules allow:
Travel on any AA/AY/BA/CX/IB/JC/JL/KA /LA/LP/MA/MX/NU/QF/RJ/ S7/XL/4M codeshare service operated by AA/AY/BA/CX/EG/IB/JC/JL/KA/LA/LP/MA/MX/NU/QF/RJ/ S7/XL/4M is permitted.
Other codeshare services not permitted with the exception of QF Codeshare services operated by Jetstar (JQ).
Additionally, travel permitted on the following airlines which are affiliated with/or wetlease providers to oneworld:
AMERICAN AIRLINES American Eagle including flights operated by Executive
Air/American Connection - including flights operated by Chautauqua
BRITISH AIRWAYS BA CityFlyer including flights operated by Flightline/Comair/Sun-Air
IBERIA AIRLINES Air Nostrum / Gestair
JAPAN AIRLINES J-Air
LAN AIRLINES Lan Express
MALEV Carpatair, Base Ltd, Moldavian Airlines (excluding BUD-KIV vv)
MEXICANA MexicanaClick / MexicanaLink
QANTAS Alliance Airlines, QantasLink operated by Eastern Australia, Jetconnect, National Jet Systems and Sunstate Airlines
SIBERIA AIRLINES Globus
I can't answer the question re:routing but suspect (i) it's allowable as Montreal and NY are both on the east coast, and if not (ii) you'd be able to fly into the West coast and then take another combination of flights to get you to Montreal.