Question about relayed motor control?

I have some 2 wire DC brushed motors. I am trying to get a relay configuration working to operate the motors (forward, reverse, off). There are 5 motors total. I am using an 8 Relay USB controlled board. It is basically an audrino controlling a bank of relays. The relays are RAS 1215 they have Normally Open, Normally Closed, and Common. The problem I am having is ground switching for polarity. Since there is no "relaxed" position on the relay that provides no contact between common and either other side, I cannot seem to get by this problem. I am pretty good at programming do you think that there is a way to put the relays in a "half open" state by telling the audrino to have a 3rd command which supplies just the right voltage to half-open the coil? Does this sound feasible to anyone else or am I better off using either more relays (I don't want to do that b/c the response time of calling upon them one at a time in code.) or should I find some relays or something that is made to reverse polarity for motors. If so they need to be USB controlled. Any suggestions?