Group + bridesmaid orders, single bride, multiple bridesmaids, mixed sizes, single ship-to. How?

Birdy Grey shipped the modern model and every modern bridesmaid-dress brand has copied it. Native Magento multi-shipping won’t do it, needs a custom group-order module on top of standard checkout. The flow:

• Bride starts a group order on the PDP (“Order this dress for my bridesmaids”). Gets a unique shareable invite link tied to a group-order ID.
• Sends link to 4-12 bridesmaids via SMS/email/group chat. Each bridesmaid lands on a curated page showing the same dress and color the bride picked, but lets her choose her own size.
• Each bridesmaid enters her measurements + picks her size variant + (optionally) personalization. Measurements saved to her customer account for future repeat bridesmaid orders.
• Single ship-to address (bride’s) by default for simultaneous arrival; or per-bridesmaid addresses if preferred.
• Payment, bride pays in full, splits via Klarna/Afterpay, or each bridesmaid pays her own line.
• Klaviyo journey chases bridesmaids who haven’t completed sizing at 3 / 7 / 14 days. Target completion rate: 75%+ within 14 days.

Cost to build: ~$8k, $15k for the custom module + Klaviyo journey. Pays back inside 6 months for any bridesmaid-dress brand at $500k+ GMV because AOV jumps 4-10x per order vs single-purchase.