If you want your group to want to include more diversity, make sure it is healthy enough to attract the right person to want to apply, to want to volunteer, or to want to move into your area.
I have been the first black person or first female for several boards, committees, awards, positions, and sometimes friends for others. Depending on the situation, it was rewarding, challenging, and at times lonely.
Fred Rogers said it best " There's a world of difference between insisting on someone's doing something and establishing an atmosphere in which that person can grow into wanting to do it."
When you have a group of like-minded individuals, understand that you could be limiting your potential for growth. Want new ideas, but make sure you are at a decision table of people who value and handle differences in opinion.