I've done a few Zen Cart sites, but I'm not sure hwo to do this. We sell invitations and offer pre-printed envelopes as an option. I've got the three options set-up as drop down attrributes just fine. But if the customer is choosing either of the second two options, I need a box for them to enter the return address they want printed on the envelopes. I'm not sure how to work that. For example, http://customcreationsunltd.com/zens...&products_id=1

Any suggestions?

Thanks,
Jim