To draw the second plot on the same axe as the first plot, you need to use the axe returned by sns.heatmap. Simplified example:
glue = sns.load_dataset("glue").pivot(index="Model", columns="Task", values="Score")
g = sns.heatmap(glue)
g.bar(np.arange(10), np.arange(10))
g.invert_yaxis()