On a renovation project where we are feeding a new panel from an existing panel. The new panel is 300 feet away. Due to voltage drop we needed to double the feeder size. Was going to install dual lugs on a new breaker in the existing panel, but it will not fit in the existing panel. Is it legal to set a junction box beside the existing panel and splice the parallel feeders together and then connect to the new breaker? Was thinking about using some ilsco terminal blocks for the splice. Want it to be neat installation. Looking for options other than replacing the existing panel. Thanks