if you want to keep the form open and pick from instances of some object, which will then be used in creating new reference attribute instances of the object instance in the form, you could DISPLAY a Custom Query.
each instance in the Custom Query could have am element which when clicked runs a process which flags the instance as one which should be used in the creation of new reference attribute instances.
then when the DISPLAY'ed query closes the Process can then Find the flagged instances and use them.