2004 dakota wiring

I have a 04 dakota q/c that I am installing webasto seat heaters in.The fuse panel on the drivers side has a 20 amp fuse installed for heated seats,I didnt even know that this was an option. How can I find where this wire goes to, since it is 20 amp and that is what I need (10 amp each side). I have looked in the back of the fuse block and tried to trace wires using a test light and a meter, it is impossible, there is also a 20 amp fuse for the amp, which I don`t have either, so if I need to I will tap into it if I could find  that wire, if you have any other suggestions,any help would be appreciated

Hope this helps, the fuse labeled fuse 2 is the 20 amp fuse for the amp, this is the best fuse to use. other 20 amp fuses are, fuse 3 radio,fuse 4 park lamps relay control and contact feed,fuse 5 wiper control feed-central timer module-frt wiper motor, and multifuntion sw.best to stay off the latter fuses.again hope this helps . these are tr out of the factory wiring manuals...bertman