Can My Father Be A Groomsman?

My fiance and I are planning on getting married in September. Originally we had planned on just having a maid of honor and my best man, but then after talking to some family members we felt it would be best to have her brothers and their spouses with us as well. My sister would also like to be up there, however, that would make an odd number of people in her line versus mine, and so I was considering asking my dad to be a groomsman. Is this ok?