A ceremony can honor family without giving every relative ownership of the decision.

Including people and handing over control are different acts. A family can be present, thanked, seated well and given a part to play, while the decisions still belong to the two or three people whose life it is, which slights nobody. Most of the difficulty around weddings and funerals comes from confusing the two. Honouring somebody does not require giving them a vote.

Decide early who is deciding, then be generous with everything else. Give relatives real roles rather than real authority. Saying it plainly at the start prevents most of the negotiating later.