Introduction

Sister Jane is a London‑based fashion brand with a devoted global following. As the brand scaled, the team needed more than a polished consumer storefront—they required a wholesale engine, tighter operations, and a resale ecosystem that reflected how customers actually shop fashion today. TheGenieLab partnered as the brand’s Shopify Plus Agency to deliver a robust Shopify build across two pillars: (1) a wholesale/B2B layer fully integrated with back‑office systems, and (2) a custom B2B marketplace (Resell Genie) that lets customers resell pieces, manage listings, and handle payouts and shipping without leaving the Sister Jane universe. Alongside this, we refined the consumer site with a cohesive Shopify theme and hardened flows for performance, reliability, and scale.

The Challenge — Wholesale + Resale, One Brand Experience

The transformation asked for a lot in one programme: upgrade the DTC experience, stand up a wholesale stack that synchronises inventory and prices from Cin7, and create a fully fledged B2B marketplace for community‑led resale with real‑world constraints like multi‑carrier label generation, fraud control, payouts, and email operations at scale. We also had to work within fashion‑specific needs—order deadlines, deposits/balances, variant/size volatility (e.g., XXS/short‑run sizes), and season‑based collections across regions (EU/UK tax and compliance nuances).

TheGenieLab’s Approach as a Shopify Plus Agency

We set up parallel workstreams with shared QA and deployment practices, using staging environments, scripted imports, webhook health checks, and GraphQL upgrades where prudent. The guiding principles: minimise friction for customers and sellers, surface the right data at the right time for ops, and keep theShopify buildmodular so new ranges, regions, and marketplace rules can evolve without a rewrite.

1) Wholesale on Shopify Plus — A Reliable B2B Backbone

Wholesale buyers expect speed and certainty. We stabilised and extended the B2B experience on Shopify Plus and Cin7. Highlights:

Cin7 sync hardening: Resolved empty orders and line‑item discrepancies; enforced address defaults from Cin7; handled currency/tax edge cases (EU tax exclusive).
Order form performance & search: Faster loads, reliable search, and quantity handling—even with large assortments and frequent variant updates.
Deposits & balances: Built and fixed flows for deposit creation, tracking and email notifications; aligned dashboard totals with discounting and shipping logic; added Windcave production support; guarded against duplicate deposit status changes.
Deadlines & restrictions: Implemented order deadlines per collection/region so buyers can’t purchase after a cutoff; added minimum‑order warnings to keep terms consistent.
Email & SendGrid: Migrated high‑volume notifications (order status, deposit/balance, shipping updates) to SendGrid, cleaning spam issues, templates, and formatting.
Theme & UX touches: Menu fixes, mobile layout corrections, reliable thank‑you flows, and clear error states on draft/confirm order transitions.

2) Resell Genie — A Full B2B Marketplace Inside the Brand

Sister Jane’s resale initiative is a B2B marketplace designed for real usage on real phones. Sellers create accounts, list items with structured condition guides, and buyers check out with consistent brand experience. We engineered the marketplace app to be operationally sound and seller‑friendly:

Seller onboarding & controls: Admin approvals, block/review mechanics, invite flows, and non‑UK seller rules. Clear status changes (Active, Sold, Rejected), and robust “My Wardrobe”.
Listing experience: Mobile‑first image capture (including direct camera upload), cropping, size/fit, composition and condition capture; enforced mandatory fields and image limits (raised to 10MB where appropriate).
Shipping automation: Parcel2Go/Evri integrations for label creation, QR codes, cancellations, and tracking; multi‑seller order logic; address parsing; nearest location lookups by postcode.
Payouts & accounting: Gift card‑based payouts via a custom Gift Card API with expiry controls; PayPal detail capture; automatic payout reports; commission rules editable in admin.
Notifications & comms: A full suite of email templates for buyers and sellers (welcome, item submitted/approved/rejected, sold, shipping reminder, item received, cancellations, returns) with robust SendGrid delivery.
Catalog & search: Filters (size, gender, condition), zoomable images, mobile fixes (footer visibility during filtering), and pricing parity between seller and catalog.
Operations UX: Admin dashboards for labels, payouts, stock add‑backs on cancellations/refunds, and quick edit flows for products, plus auto‑complete inputs coded against live product data.

3) Shopify Theme Customisation for a Cohesive Brand

The consumer site and marketplace share a common visual language, rooted in a tuned Shopify theme that protects brand equity. We:

Harmonised typography, spacing and mobile breakpoints; corrected image ratios and sticky add‑to‑cart behaviour.
Fixed menu interactions and cart drawer reliability; reduced reloads (AJAX where appropriate) to keep shopping fluid.
Optimised product pages for speed and clarity (size guides, variant/availability feedback, gallery behaviour, and low‑stock states).
Ensured marketplace UI (My Wardrobe, seller menus, commissions) matches the brand’s DTC polish.

4) Shopify Custom Integrations & API Upgrades

Beyond Cin7 and carriers, we standardised on GraphQL where it added performance or clarity; we built import scripts to seed and sync data; and we hardened webhook subscriptions with retryable command jobs. Highlights:

GraphQL uplift: Product import/publication mutations; customer and seller invite flows; order lookups; publication management across channels.
Robust webhooks: Tracking updates, label events, order cancellations, and payout automations processed via reliable background commands.
Scripted operations: Bulk product sync from the DTC catalogue into marketplace contexts; admin upload tooling for labels and assets.
Payment stack: Windcave for B2B deposits/balances; PayPal for seller‑side payout identity; gift card issuance for marketplace earnings.

TheGenieLab’s Approach as a Shopify Plus Agency

Testing, QA & Continuous Improvement

Fashion retail evolves weekly; so did the backlog. We embedded QA across sprints: staging environments for both B2B and the marketplace, regression suites for deposits/balances, and checklists for mobile listing and checkout paths. We monitored webhook failures and retried via command processes, and we used weekly review meetings to prioritise real‑world pain points (e.g., duplicate emails, variant size gaps, or order dead‑ends).

Mobile first:Camera uploads, seller menus, filter dots, and footer behaviour verified on small screens.Order certainty:Guard‑rails around deposits, discounts and collection deadlines to prevent mismatched totals.Email hygiene:SendGrid templates, domain warm‑up, and spam mitigation for reliable notifications.Operational clarity:Admin stock add‑backs, payout listings, label states and audit trails.

Results

Sister Jane now operates with a multi‑channel commerce stack that matches its ambition:

Wholesale velocity: A dependable Shopify Plus B2B flow backed by stable Cin7 syncs and deadline‑driven ordering.
Community commerce: A branded B2B marketplace (“Resell Genie”) that keeps product lifecycles inside the Sister Jane world—driving loyalty and retention.
Unified brand: A tuned Shopify theme across DTC and marketplace experiences, with fewer UI regressions and faster paths to basket.
Operational control: Label automation, payout governance, and webhook‑powered status updates reduce manual chase work for the team.
Future‑proof Shopify build: Modular app and integration layers mean new carriers, regions, or payout rules can be added without ripping up foundations.

What Made the Difference

Domain expertise: Blending DTC, wholesale, and recommerce into one coherent brand journey.
Engineering rigor: GraphQL where it counts, resilient webhooks, and background jobs instead of brittle one‑shot scripts.
Design stewardship: Theme decisions that favour clarity, speed and on‑brand details (and less “mystery meat” UI).
Relentless QA: Weekly triage on live issues; staging parity; and “close the loop” fixes on deposits, discounts and emails.

Conclusion

Sister Jane’s transformation shows what’s possible when a Shopify Plus Agency treats wholesale and recommerce with the same care as DTC. The result is a Shopify build that balances brand, operations and community: a tuned Shopify theme for shoppers, a reliable B2B backbone for buyers, and a purpose‑built B2B marketplace that keeps customers in the ecosystem long after the first sale. With the foundations in place—stable Cin7 pipelines, carrier labels and tracking, SendGrid email hygiene, and payout automation—Sister Jane is set up to move faster, experiment more safely, and scale globally.