Harmone5, our district is the same. School staff period can't be on the board. They can vote as members. We were told it is because the principal can influence her staff. We don't have any teachers that go to our meetings anyway. They haven't for about two years. Our new principal doesn't come either.
At the previous school my daughter attended, there were two VP positions. THe 1st VP was a parent and the second VP was a teacher. When it came to elections, the parents choose the 1st VP and the teachers nominated and voted for the 2nd VP. We were lucky though, that school had a huge teacher involvement. One that our present school does not. (I am suffering from a lack of withdrawl!)
Since it's a Parent- Teacher organization our groups always considered Teachers full members.
In elementary PTO, our Executive Board was large by design as it conducted all the business with general meetings only occuring twice a year. We had 25-35 members which included the officers, parent rep from each grade, committee chairs, plus 4 school positions (Principal, Vice Principal, Two teacher reps appointed by principal).
All were voting members, except school employees couldn't hold the 4 elected officer positions (because we had defined school positions on the Board.)
In our middle school PTO, it's much less formal but teachers are still welcome to participate equally.
I don't believe there would be any conflict of interest for them to serve. (Parents also benefit via programs fro their children.) However, ANY Board member should abstain from a specific vote in which they might have a personal stake. That's just good business practice.
I believe it was conflict of interest when voting on funds for their spcific content area. I have a call in to the district on the legal side, as the man speaking was a CPA.
If your bylaws allow teachers and the principal to be a member, why wouldn't they be allowed to vote on any matter? Why would the IRS have a problem with that?