Is it safe to have an elective ultrasound at 14 weeks while extended family is in town? i will have already had 3, including the nuchal scan.

Yes BUT: Are you having this elective study just to entertain your out of town relatives? If so, you should reschedule to the next indicated time as determined by your ob. While there has been no demonstrable bad effects to fetuses by ultrasound, prudent medical practice is to limit exams for only medically appropriate reasons and not entertainment. Your insurance is not likely to cover such exams.