OK, I read the part in the manual you are talking about, what I get is a 'function synonym' is just a synonym called from a function.

I believe that your example is already possible. You just need to define the skills you want (page 104). You can then just call the action when needed, you dont need to use the create command.

It would just be like adding health using a function or action, I like functions better since they are not called at the start of the game and you dont get those dreaded empty synonym errors.

Example:

Function add_health()
{
if(My._health < 25)
{
my._health += 25;
}else{
my._health -= 25;}
}

Hope this helps,

Brandon