You cannot use both FA and FACE datasets. Similar you cannot use both LB and LBHM.
If your FA domain consists of combined records from FACE, FAMH, FAAE and FACM datasets, then you need to keep split datasets in a special folder. It used only in case of very large size of FA domain which requires splitting into smaller datasets for better usability. See FDA Technical Conformance Guide for details.
If your split datasets are not related to FA and have additional records, then name of domains should be different. For example, custom ZA domain instead of FA.
In the current company all the standard specs were using only FA but not FAxx, however based on the OVRR guidance we recently implemented FACE for Vaccine trials .
Hence resulted in FA and FACE . Moreover these datasets are not greater than 5GB .