Hi @blaz , it sounds like the best approach would be to use custom hidden profile properties when asking your customers to self-identify in a post purchase flow. This Klaviyo article talks you through it, but essentially you would use this link 

{% update_property_link 'profile_property' 'property_value' 'redirect_link' %}

Where ‘profile property’ equals the property you want to identify (ie. Type of buyer) and the ‘property value’ is the value for each type - in your case perhaps “gift” and “self” - important to note that the spelling and capitalization matters - if you create a property of Gift and gift they will not be counted as the same value in Klaviyo. 

Good luck,

thanks @KatherineB 

Would it be that everyone goes into the post purchase flow and the first email is where they self select as a ‘buyer type’?

In this instance we now have three groups of buyers

1. self user
2. gift buyer
3. Unknown (for people who haven’t self selected)

Lets say I want to send the gift buyers down one email sequence and the self users/unknowns down another email sequence.

Would that be done in the existing post purchase flow or would you put them into another/new ‘self user/uknown post purchase’ flow or ‘gift buyer post purchase flow’?