This is how it works.
When you take up your First or Second Claim membership you will see on the sign up forms this question:

Select this (change No to Yes) and you will see the discount code FAMILYMEMBERSHIP

Once you have joined (so please follow the instructions for an adult, First or Second claim
membership first) you can then enter this code into the coupon field on the Associate and
Youth membership forms and the value will be reduced to zero. 

To help us tie everything together, there is an additional field on the Associate and Youth
membership forms asking if this is part of a family membership. If it is we ask the ‘lead’
adult member to provide their name and email address.