How to handle URL redirects after migrating to a new website?

[TheMagicCrayons]

Dear all

I've spent a whole chunk of time rebuilding a website within Shopify only to discover that a large number of my old URLs cannot be redirected. So most of my content that's out there in social media is no longer going to link a page or blog post.

Issue
URL Redirects

Example: Old URL from previous website
https://www.ginzawatches.com/?post=citizen-watches-mens-ca0649-06x-eco-drive

New URL in Shopify
https://ginzawatches.com/blogs/ginza-watches/citizen-ca0649-06x-brycen-solar-watch-review

The URL redirect function within Shopify does not work. I spoke to Shopify support who indicated that the "/?" in the original URL is the issue.
As it requires custom coding to resolve they were unable to provide that.
On my previous website and hosting I'd edit the htaccess file.

How may I proceed? 

Thank you

Tim