First, I assume you are using the Gather E-mail addresses and Textible Phone Numbers tool. If you are using the selection by Household Status, you are correct that it will only return the primary email. However, if you use the specific selection criteria (Club Name, Member Type, etc), it will find any linked emails to someone meeting the criteria. So, the key will be how you set up your contact records. I tested this for one family, so I think it will get you what you want. Here's the example:
Say James is a Sparks clubber in this 50-50 situation and you need to be sure the email goes to both parents. In the Member Form, open the contact record. In the row that has Mom's email, set the Member Link field to James. Also in the row that has Dad's email address, set the Member Link field to James. When you gather email addresses for Sparks clubbers, it will find any email address linked to a Sparks clubber, in this case James, so both email addresses will be returned.
If there are multiple children in the same household in the same situation, say Jonah is a T&T clubber in the same family also 50-50, you would need another set of records with Mom's email linked to Jonah and Dad's email linked to Jonah so when you gather addresses for T&T clubbers it will also get both addresses.
The process removes duplicate email addresses, so if you run it for "All Clubs" and "Clubber" or "Sparks and T&T" and "Clubber", you should only get Mom's address once and Dad's address once even though they are linked to two clubbers.
Give it a try and let me know how it goes!