Is Nepotism illegal in the state of Maryland, and more specifically within the PG County public school system

I have worked in one of the PG county schools since 2014. In these last two years I have taken and passed the Para Professional with scalel score of 471. The highest scale score for this exam is 480. I am 64 and have worked as a DA with very little pay in that position. I have spoken with the principal of this school for several months about being considered for the para vacancies she has had in the past and the 3 she has now. She said that the Board will review applications and select from their applicants for the interviews at my school. When I asked her if there was anything she could do to intervene on my behalf for one of the positions, her response was "no, that the Board makes the decisions" In the meantime, the nepotism that exists in this same school is not only overwhelming, but certainly, unfair to people who take, pass and apply for vacancies on a fair basis. I am 64 and have worked for major law firms in New York for 45 years totally. Now working every day for the school and not given a fair opportunity for a promotion. The principal's own niece who was a Dedicated Aide like myself when I first started there has been moved up to para professional since last year. There are two sisters working as paras, one teacher has a nephew working as an ISEA, the maintenance man's granddaughter is a para and the niece of the two sisters is working there as a para. I want an answer to my question regarding nepotism being illegal, and most importantly do I have a case for discrimination because I am 64. Please help me with this answer.