Combining custom and out-of-the-box xapi statements

Hi Anneleen, did you get anywhere with this effort?  I am wondering also how to mix the default xAPI statements that Storyline constructs to report on graded questions, while adding my own custom statements.  

The tutorials that Doug mentions, and all others that I've looked at, tell you how to do one or the other only.  I think what I want though is one file (probably the tincan.xml file that's produced when you export from Storyline as xAPI) that has both out-of-the-box statements AND custom statements, so that the LMS/LRS reads them as one cohesive data set.

Have you been able to do this, or does anyone else know how to create a combined output?  I assume that the activity ID has to correspond with the one that Storyline will use, and I don't know which other elements need to be in the javascript in order to have it combine nicely with the out-of-the-box statements. I'm a beginner coder and I'm trying to use the xAPI compatible LMS "LearnUpon".