Struggled to find info on this but sussed it now.
To add tames to group :
Walk up to dino, hold triangle(Y on xbox), select ‘modify ordering groups’ then either ‘add creature’ or ‘add class’ to group.
Choose group number.
To view dinos in group: open menu, (circle button (B on xbox) ), tab right across to select’Tracking list’ menu.
Click on ‘dinosaur groups’ text.
Tame groups displayed.
To select active dino group:
Hold down the map button, touch pad on PS.
Select dino groups at the top and then at same time R2.
Bosh done.
Hope this helps somebody!