Doubles dart teams

I have a problem with the teams that have alternates that play as much if not more than the original two team players. I thought it was doubles with an alternate, not a three man team. Isn't the alternate only supposed to play when one of the team members CAN'T be there to play? But it seems we have teams that all the players, including alternates are all there and the captain or other team player is not playing and the alternate is. I have talked to numerous people that play on tuesday nights and they agree on the subject. I think if we are going to have rules then we need to abide by them, ALL of them, not just the ones that are convenient to certain people.

One rule is that if you are throwing darts and your partner is keeping score, they should not be able to tell you what to do or what to throw at. Unless they are sitting they should not be aloud to do that.