Sub form use for lookup to populate multiple fields

Hoping someone can provide a good method to do the following.

I have an app that has four fields (Receiving Location 1-4) that is referenced to a table with several thousand records. The user needs to identify which locations a product is being shipped to (can be split up to the four locations). Currently the four fields are setup as refs to the receiving locations table, but with so many options that is messy for the user. What I would like is to have the user redirected to another form that would allow them to select state, city, and then see and select the receiving location. They would do this on each of the four fields to populate that location.

Any ideas on the best way to do this?

I may advise adding 2 extra columns to your sheet for each location ref. Then you can filter each ref column values with setting an expression like below in the Valid_if property of each ref column: