i have 1400+ stores, and no performance issues

Do you have any performance issues on the single customer record itself?

@AK47 Do you manually add addresses in the customer record for burlington or do you do CSV imports for the address?

the majority of our stores were imported from CSV, but if we have to edit or add one store, we do it from the UI with no issues.

I was going to ask how you got it to write under a sublist but totally missed the check box option in the setup process