Greetings! Longtime lurker here at statalist, but this will be my first post. So please let me know if there are any details I omitted that would make responses easier.
Using Stata v15.1, I ran a multilevel logistic regression model using the melogit command to examine how the interaction of X*Z predicts Y. Both X and Z are continuous variables. After running melogit, I used the margins command to examine the interaction of X*Z. Since X and Z are continuous, I specified the values =(-1SD, mean, +1SD) for both variables to be computed. I then plotted the results, which I've included here:

Array

Now I would like to test whether the means (red circle) and slopes (green circle) for the three groups are significantly different from each other. Unfortunately, I have not been able to figure out how to do this using contrast or margins commands. Any help with this issue is greatly appreciated!