How to add IF-ELSE Condition inside XML

Question

I have the below XML

<controls> 

<control>

<controlId>CheckBox4</controlId>

<controlType>CHECKBOX</controlType>

<controllabel>Include Switches</controllabel>

<required> false </required>

<errorMessage>Set Switch Status</errorMessage>

<cssclass> switchfilterfield </cssclass>

<order>2</order>

<defaultvalue>Y</defaultvalue>

</control>

<control>

<controlId>lb_trades</controlId>

<controlType>DROPDOWN</controlType>

<controllabel>Trade Filter</controllabel>

<dependentControlId>lb_fundids</dependentControlId>

<oncheckboxclick>true</oncheckboxclick>

<required>false</required>

<order>3</order>

<query>436</query>

<defaultvalue>Show Subs &amp; Reds</defaultvalue>

</control>

 </controls>

 

I need a IF condition under Trade Filter Dropdown Such that if Checkbox4 is checked then Queryid  = 436 should change to 437.