Checkout ui extension remix app

Topic summary

A developer is building a Shopify checkout customization using a JavaScript-React Remix app with UI extensions. They’ve successfully added custom input components and can programmatically populate the city field in the address section. However, they’re encountering issues writing to the firstName and lastName address fields. The developer is seeking guidance on whether modifying these specific fields is possible and how to accomplish it. The discussion remains open with no responses or solutions provided yet.

Summarized with AI on November 1. AI used: claude-sonnet-4-5-20250929.

I’ve been working on javascript-react “remix” app to customize checkout and i’ve learned to add inputs and other components, and i’ve been able to fill in the city field (address) but i couldn’t write in the firstName/lastName field (address).

Some clue if is this possible?

Thanks