Any advice on how to separate the Real Estate Enterprise for the 199A Rental Safe Harbor in the following situation?

1 Rental is a Building with multiple units of which is some are Commercial businesses and some are residential apartments. (one set of books & records)

1 Rental is a Room Rental in taxpayer's primary residence. (second set of books & records)

For the aggregation requirement that commercial and residential cannot be combined into one enterprise, yet separate books and records must be kept for each...