Unfortunately, the only way to deal with related tables is to use SQL queries. The Riverside example you refer to has some good example code to look at, but you have to open the AXF and check out the VBS files inside to see the parts that deal with tables.
Basically, you have to open a Datasource and feed it an SQL command. The Riverside example seems pretty complex taken as a whole, but I'd recommend just trying to pick out the bits of code necessary to perform a query (in Inspections_onSetActive in the example), add a row to a related table (InsertInspection), modify a row (UpdateInspection), and load values from a domain table (FillCodedValues). If you're modifying / adding anything to your tables or feature classes (you can manipulate the feature classes using SQL in the same way) make sure you use the AXF_Status / AXF_Timestamp fields to flag the records as being updated, since that's how the check-in process knows to update them.
When trying to save values to a related table I'd recommend doing it during "onunload" of the form, since the feature the table is related to needs to be added before you add a row.
Hope this helps!
