If I read you post correctly why not just insert a new check box at the
location you want one?

If there is some reason, you can try changing the binding. Go into the data
source, select the group you want the control to bound to, click Add, give it
a name, select the type and data type then click OK. Then right click the
check box and select change binding. Find and select the new field or group
you created and click OK.