My expertise is with numerology rather than astrology. So I'll address the numerology aspect. Perhaps an astrologist can help you with the astrology part.

Because the energy represented by numbers tends to attract energy with similar resonance, it is not unusual for several people in a group to have either the same name numbers or name numbers that are compatible with each other. That the group consists of only three individuals and all three have the same first name number would be less common, but not highly remarkable.

There are likely to be other commonalities related to numerology. Use the diagrammed numerology chart with each of your names and birth dates to see if I am correct.