Two many power wires going to fuse box! Is there a better way?

What you really need to do is figure out how much total current you're pulling through that circuit by temporarily using an ammeter in series. My guess is you may be alright if you're not pulling more than the circuit was originally designed for. Whatever you do, do not use a bigger fuse unless you're sure of what you're doing. If you're really pulling a lot of current use another fuse and/or a relay if needed.