BC added allowing multiple posting groups to the base business central package a few releases ago. There's two things that were left incomplete and feel significant to really complete the feature offering.

First - Add the "allow multiple posting groups" toggle switch to the Customer Template page. In an environment using this feature, either classes of customer or all customers should be able to have that feature defaulted on to ensure consistency of data & reduce opportunity for error/complexity of knowledge on the employees who set up customers. I've checked personalization & role center tailoring, and its simply not available without a customization at this time.

Second - Add the customer ledger entry-based posting group to the Aged Accounts Receivable report dataset. Generally if there are multiple posting groups for the same customer, there's a good chance the transactions will be landing in different accounts receivable G/L Accounts. Current report filters only cover the customer's primary posting group as a filter, and the data does not allow for a user to add the transaction-level posting group used without a customization/report extension. This breaks the ability for the out of the box report to support reconciliations to the general ledger. If the transaction level posting group would be added to the data set, a much simpler report modification could be completed to support receivables account reconciliations

I think both changes are small, but would significantly reduce barriers to use the feature.