If a family profile is set to, "Never schedule this family without all of its members," and one family member is scheduled without the others, then the "Conflict Report" from the Reports menu on the schedule will list this as a "Family is split" error. However, if two or more members of a family are scheduled, and there are still more missing members of the family, then no error will be shown.
The program works this way instead of reporting errors anytime a family member is missing to both reduce the time it takes for the auto-scheduler to run and prevent error messages from appearing when they should not be. That makes things simple enough for MSP to calculate in a reasonable amount of time.
So the only time the "Family is split" error will show up is if there is only one family member scheduled for the service. If there are two or more family members scheduled, no error is shown.