Violion plot with statistics

Hi
I am using Seurat for scRNA-Seq analysis. Along the analysis, i used Seurat’s VlnPlot function as the following:
VlnPlot(Myeloid.object, features=”Mki67″, split.by = ‘Sample’, pt.size = 0)

The feature is then represented in a different color for each Sample, and is divided by cluster.

I want to add statistics the each cluster, and check whether the expression of that gene is significantly updown regulated upon treatment. Is there any smart way of adding statistics (**) and lines that defines the groups compared the this ggplot that takes into account the nature of the data (single cell RNA sequencing)?

Thanks!