It's probably best to avoid completely starting over, and creating a form based off of a webservice has its own large limitations, as I can see in another thread that you've already discovered.
For whatever reason, InfoPath doesn't allow using the Add Row/Delete row actions on repeating tables bound to a secondary data source, but there is a way around this. qRules (see the banner below) provides the Insert and Delete commands that can be used to add and remove nodes even in a secondary data source. Just create buttons that use these commands and you're all set. Why not give the free trial version a try?