I'm not sure there going to be that interested to get involved or manage this, thats down to relatives, however, its worth an email to them asking what he needs to do now to avoid problems later.
Each departure and re-entry restarts the 90-day clock; your next check-in will be 90 days from your most recent date of arrival.
You may have to report your address on a TM30, this year it changed that if your returning to the same address you don't have to report, however, some offices still want you to report, check with them.