Merging orders for a specific customer

[studio-umbrella]

Hi all!

I'm looking for a solution to merge a particular customers' orders in order to consolidate shipping. Heres' the scenario:

A customer has a subscription for a group of products ("box") that they get monthly. If this customer orders something additional (either same day or let's say within a week), it would be great to combine these orders so that they can both be shipped in the same box, saving costs for the customer and for the merchant.

I can't realyl find an app to do this, and the Shopify Scripts and/or Flow doesn't seem to give a solution for this (the merchant is a Shopify Plus member).

Thank you for any help!!