Is this a Flying Blue booking?

If so, you can call up to change the booking to a simple CDG-ORD flight. Make sure you find a date of departure on which the price in miles for CDG-ORD is the same as (or even better, less than) what you already paid; otherwise, you will have to pay the increase in fare (i.e. pay extra miles). You will also have to pay the change/cancel fee which is currently €70 (unless you are Flying Blue Platinum or Ultimate)

You could also enquire about the possibility of changing your existing ticket to one with a "stopover" in CDG; so, move your current FRA-CDG ticket a few days earlier than it is currently booked. Again, this will also require the payment of a change/cancel fee, plus any increase in the cost of miles that may be required due to the date changes.

Under no circumstance should you leave your booking as it currently is - FRA-CDG-ORD - if you intend to only fly from CDG-ORD. If you miss your flight from FRA, you will not be allowed to board the connecting flight from CDG-ORD unless you pay a penalty fee (which, in the present case, would be €500 if your ticket is in Economy or Premium Economy and €1500 if your ticket is in Business/La Premiere). Alternately, you can just buy a new ticket; but buying a new one-way ticket on the day of departure - rather than "fixing" your ticket now, 11 months ahead of departure - will be very, very expensive.

All fees mentioned above are per person.

https://wwws.airfrance.nl/informatio...o-cg-airfrance