Hi,
Probably the easiest approach (depending on your layout) would be to combine the shrubs into groups of 3/5 and add these groups as items in the Geometry list. If you disable the Keep Group Hierarchy option, the shrubs will be treated individually. You can then introduce variety by randomizing the Transform settings - Translation, Rotation, and Scale. Please find attached a sample scene that demonstrates this approach. I hope you find it useful.
Best regards,