Creating graphs in xymon

I have some custom data I collect from different hosts, and generate rrds from them. One problem I have is that not all hosts have all the same data. Ex: host1 has the series data1, data2 and data3 but host2 has only data1 and data2. If I in hobbit-graphs.cfg define all tree data series, the graph will fail for host2 since this rrd dont contain this data.

Is there a way of defining the graphs.cfg with using variables? Would like something like this to be possible: DEF:$data=file.rrd:(data\d):AVERAGE LINE2:$data#@COLOR@:$data

The @COLOR@ is working.

Any one that have done something like this?

Øyvind