I applogize that I have little experience in 2.8, but I realize groups (ctrl+g) are gone.
I have many old blender files with makehuman characters that have many groups for clothes and props.
What happens when I open an old .blend in 2.8?
Are the old groups still honored by 2.8 but converted to something else? or is the relationship lost?
2.80 uses collections, however not sure if 2.80 going to transform old groups into them. Old saves aren’t really compatible with 2.80
Usually i separate group onto layers. After 2.8 import every layer become collections.
Another way is to use the command File > Append > Collections. This way import groups placed onto different layers.
Hope this help