Rrrrrrr, need help on this one.

I don’t know how I can add a fuse when it has 4 prongs and I’m not going to hack up my horn relay harness. I’m in the process of buying another horn relay. At $20 a piece, I hope it doesn’t burn up too, lol !
I didn't say to add a fuse to the horn relay circuit. I said, if you suspect the horn relay could be causing the fuse to blow simply unplug the relay and replace the blown fuse. If the fuse does not blow with the relay unplugged it could have been the issue. Simple diagnostics.