What i want to do should be easy to do via URL hack, but looking at legitimate ways of doing this. I want to create a child invoice line item from parent invoice and set the save url to the parent invoice.
I had the thought of approaching it using URLFOR and $Action but can't even get it to set the parent id. Saw some old threads on success that indicated you could pass the field IDs as parameters but system won't allow for save, and this seems little different from URL hack. Can't find any docs on what url parameters, if any, are officially supported on $action.
So, then, what is the supported means of doing this? Do I have to replace the line item page w a vf page and use an extension to override the save behavior? Is there a simpler supported means of doing this?