Easy way to get this custom module to work with multiple Nodes (NID's)
Would have been good if you explained what the module does so we don't have to read through the code to understand the module.  

I am going to assume you mean the nid condition in the query.  

The condition function of the query object defaults to 'IN' if you send it an array.
eg.

$nid = array(4, 5, 6);


and then:  

-&gt;condition('nid', $nid)


will check nids 4, 5 and 6.
If you want to check all submitted webforms, just remove the nid condition.