Did you wire in the ISO connector yourself or did it come with the car? In the latter case doublecheck all wires so that they actually match with the ISO standard...

As to the remote wire, I'd connect the wire that goes to your amp(s) to the male ISO connector too - that way it's all in one plug, neat and tidy.

If there's no wire currently in the position for the remote turn on wire in the plug, I'd try to get one of those crimp/solder pieces that fits into the connector and make it a part of the ISO connector. If there's a lead for the remote in the plug already, I'd connect the wire running to your amp(s) to that one (solder & shrink tubing), ie make the splice on the "car side" of the connectors.

/Michael