I'm not sure if Anglia Plus is available with a Family & Friends railcard or not.
GroupSave is offered where the fare is set by a select group of TOCs (I'm not sure which ones, there may be info on the useless NR website), on selected point-to-point ticket types, for example Off Peak Day fares.
I'd scrap all GroupSave fares and introduce a National Railcard with common conditions giving 1/3 off for all on any ticket subject to a minimum fare before 10am.
The current complicated set of discounts is confusing and unfair, with a huge bias toward the South East.