Adding Skymiles number to Flying Blue Award Ticket

Hi,

I have a Flying Blue award ticket-- flying on El Al-- that I want to add my Skymiles number to. Not able to do so on Air France or El Al's website. Any ideas how I can do this? Similar question was asked here (https://www.reddit.com/r/delta/comments/1bqnk7g/adding\_skymiles\_number\_to\_klm\_flight\_booked/) and said to do it through Kenya Airlines but that website seems to glitch out when I try to modify my reservation on there... Any advice apprecaited!