Ribbon groups within a group

[oseitutuSamuel]

Hello Guys,

I have created a custom Ribbon with different groups, say "groupA"; "groupB", "groupC" etc. The top level groups work fine.
I need to create sub-groups for groupA. That is when I select groupA (one of the main top tabs), I want to get a set of groups (tabs?) that all belong to groupA (ideally
all showing below the groupA tab). This is proving tough as the children tabs always appear on the same level as their parent. It appears that I cannot place groups within a group. Is there a way to do this?

Thanks
Samuel