Many times we have different departments within our company that could be saved as a group under contacts. However my contacts in one group could have vastly different work. Person X in Group1 could be much better to ask about Product Z than person Y might be.

If I could add a group within another group me and my colleagues could avoid fracturing our contact list so massively and make it way more effective. The main group could be named "Department 1" and the subgroup within the main group could be "Product Z"

This is not possible today and it wasn't possible in Skype for Business. Please improve this.