Flying Blue (Air France, KLM, and Other Partners) - Booking a GOT-CDG-MIA-CDG-GOT ticket with ability to change return date

My parents want to fly the above route departing GOT around Dec 10 and returning from MIA around Jan 10th.
1)What is the span of dates when fares go up, around Dec 15th until Jan 4th?
2)Since my grandmother is not too well my parents also want to be able to change the return date if need be. Most websites seem to only sell tickets which are non-refundable and non-changeable. What are your receommendations for finding a cheap ticket where the return is changeable?
Thanks in advance for your help.

1. ex-Scandinavia, the higher season is 16DEC - 31DEC incl.
2. fares ex-Scandinavia are comparatively restrictive vs. other markets. They would have to pay a significantly higher fare (3x or more) to get the kind of flexibility they are looking for. Also note there is a 1 month max stay condition.

By comparison, fares ex-Germany have slightly less restrictive conditions, e.g. change for a fee.

Can they start their journey in HAM or maybe get some good travel insurance to cover the eventuality ?

hth

My parents want to fly the above route departing GOT around Dec 10 and returning from MIA around Jan 10th.
1)What is the span of dates when fares go up, around Dec 15th until Jan 4th?
2)Since my grandmother is not too well my parents also want to be able to change the return date if need be. Most websites seem to only sell tickets which are non-refundable and non-changeable. What are your receommendations for finding a cheap ticket where the return is changeable?
Thanks in advance for your help.

My suggestion would be simply to do the booking with AF over the phone. You can, on the website, ask for the fully flexible eco fare but that will be a very expensive one as stated before, you will probably have some fares in between which would enable your parents to change their return for a fee as long as there is space in the required booking class.