You can't parent one part of a figure to another. You could either multi-select them and use the dials to set the bend to the same value, or you could use a script to make an ERC link: there was recently a thread in the DAZ|Studio Discussions forum at DAZ where I gave an example, in that case hooking two props together. The code was

var hinge = Scene.findNode( "LidHinge" ); // thing
you want to make a slave<br></br>
var axle = Scene.findNode( "HandleAxle" ); // thing you
want to slave it to<br></br><br></br>
if ( hinge && axle ) {<br></br>
    var handleRotControl = axle.getXRotControl(); //
Master control<br></br>
    var hingePosControl = hinge.getZPosControl(); //
Slave control<br></br>
    if ( handleRotControl &&
hingePosControl) {<br></br>
    var ERCLink = new DzERCLink(
DzERCLink.ERCDeltaAdd, handleRotControl, 1.1111, 0); // 1.11111 is
a conversion factor from degrees to cm<br></br>
    if ( ERCLink ) {<br></br>
       hingePosControl.insertController(
ERCLink );<br></br>
    }<br></br>
    }<br></br>
}

if you know anything about coding you should be able to adapt that to your needs - you'd want the same rotation control on both items, for example..