Is it possible to prevent saponification by modifying free fatty acids? Not big on chemistry so this question might be a bit out there. It is my understanding that a soap molecule is made up of a free fatty acid and lets say a sodium ion. Correct? Would it be possible to modify the free fatty acid (with a solid or liquid substance) in such a way that when it comes in contact with the sodium ion it wouldn't be able to form a soap molecule?

Thanks
In principle You can replace the Sodium ion with any other cation. But all You get is another kind of soap: Potassium gives a smoother substance, Calcium/magnesium gives the soap-stone you see in washing machines, etc.

Another possibility is to esterify the fatty acid with an alcohol. This is widely used in the industry to produce non-ionic surfactants, and these do not react with cations. But off course, then it really isn’t a fatty acid anymore.