Our customer records can be linked to multiple AWS IDs. What is the best way to track this in NS? A custom multi-select entity field sourced from a custom list of AWS IDs OR a custom record where customer is marked as the parent record? The data value is just the AWS ID which is why I'm thinking that custom record might be an overkill. On the other hand, I find it challenging to report on a multi-select field (and import although we won't most likely do it in this case).

if the relationship is one to many then your option of custom record with customer as parent would work, then use the combination of saved search and custom subtab to the related AWS id's as a sublist in the the customer record.

Thanks!