Flat rate shipping while using carrier accounts to purchase labels?

[pcebo]

Currently I have several flat shipping rates and use Shopify Shipping to fulfil the orders and buy shipping labels (Canada Post). This workflow works perfectly for me but I can't take advantage of Canada Post Commercial rates when purchasing the labels. 

There are many apps that allow me to use my Canada Post Commercial account to get the better rates, but they all seem to work with carrier calculated rates only. This is an issue because it is next to impossible for me to setup all my products with weights and dimensions in order to get accurate calculated rates. As such, what I really want is to keep my flat rates, but be able to purchase the labels using my Canada Post Commercial account.

Is anyone aware of any apps that would allow this?

[Anindita]

Hi @pcebo,

You can easily achieve this using Shopify Multi Carrier Shipping Label App. This app allows you to set flat rates and generate labels using your Canada Post commercial account.  The app automatically chooses the cheapest Canada Post services based on your product dimension, weight, etc, and generates labels.

[pcebo]

Thank you @Anindita. I've tried this app and unfortunately it does not meet my needs. I'd like to continue to use Shopify to fulfil the orders and print the labels, but with the ability to utilize my own shipping accounts.