Filtering a table based on values within a nested table

While I know I could expand the field and then apply filters in the UI, I'm ideally looking to pass the filter in the initial call, as there are limitations in the number of rows I can pull back - so it would be more ideal to expand the RecordType field and filter for that AND filter in the business unit in one line... I'm just not sure how to write the expand and filter lines into one command.