I don't know if you can add subfields. The subfield example you show is a Bluetooth SIG standard profile with "universally" defined application usage for those bits, and hence why the bits are defined; to make sure people use them correctly in implementation. The profile/BLE editor doesn't seem to have any option that I have seen that allows the subfield to be added/created. You could try editing the text/data file directly to see if mimicking the format of the other profiles data will have the editor display it the same way, but I wouldn't be sure of it.
Currently there is no option to add subfields for the charcateristic data.