Pass _device_id to sibling device as a property in XML??

I am trying to send the device id of a block to another block as a property in a <customdevice>.pres.xml file. When I attempt to use the syntax:

<property xpr:name="'cardslot_1_id'" xpr:value='io_1_device_id'/>

it always returns zero, no matter what the actual device id.

Using this syntax:

<xpp:evaluate expression="slot_1_id=evaluate('io_1_device_id')"/>
<property xpr:name="'cardslot_1_id'" xpr:value='slot_1_id'/>

I get an error that 'io_1_device_id' doesn't exist even though the device 'io_1' exists. Error message reads:  label_t::evaluate()--"access to undefined term"

Using the syntax:

<property xpr:name="'cardslot_'+i+'_id'" xpr:import='io_1_device_id'/>

causes NWare 1.4.4 to crash...!

The property is defined as a positive_int in the <childdevice>.if.xml file and replacing 'io_1_device_id' with a random integer gives me the result I am looking for...only I don't want a random integer, I want the specific integer that is the device id of io_1!

Can anybody give me a whack on the side of the head to get through this???

Thanks for your help!!!