End of Slide using a non-timed webobject (using BranchTrack in Storyline 360)

I am importing (embedding) BranchTrack into a Storyline 360 as a webobject.  The BranchTrack portion is not timed and is finished at the user's/ viewer's own pace.  I have the Next button hidden until the timeline ends but would like it to appear when the user finishes the BranchTrack portion in the web object.  My question is twofold:

1) If I am able to push a variable value from Branchtrack while the slide plays to make a condition in which my Next button, will Storyline accept/ acknowledge it?  My thought is that Storyline will only look for values when it is told to (at the beginning of a slide, end of a slide or at a preprogrammed action).

2) Is there another way to make storyline know when the end of a slide is beyond the timeline (so that I can tell the Next button to show when the user finishes the Branchtrack scenarios)?