You can create Family Memberships easily in TidyHQ.
Select Memberships > +New > New Membership Level
Most of the fields are the same as an Individual Membership, but for Family, you need to select Family from the Individual/Family drop down under Membership
You can also now select the option of whether or not to make Children an option or not.
Once Family is selected, you have multiple pricing options:
In the above example, for the first Adult in a Family, the price is $50, with subsequent (unlimited) adults at $20. There is also a price for the first Child being $25 with the second and third children $15 and then subsequent (unlimited) children $10. You can, of course, choose to have a nil price for the children or the subsequent adults.
You can then determine which fields need to be collected for each type within a Family.
Result (Admin view)
The Family details will appear on the Contact/Member's information, showing additional Adults and/or Children included in the Family membership:
Results (Contact's view)
When the Member (Contact) views their details, they will be able to see and click on the Family members associated with their membership.