Hong Kong airport express Group Tickets/Packages

Is the Group Tickets/Packages only valid for one way or can it be use for same day return?

i will be transit in HK for 10+ hours, we are 3 adult, 1 child 7 years old, and 1 child 2 years old. if i purchase the Group Ticket for 4 person, will i get free same day return? or i have to purchase again for the same day return trip?

what is your suggestion for this situation ?

thanks