private void AddRegistrationPetitions(Registration registration, List<CeremonyParticipation> ceremonyParticipations, ModelStateDictionary modelState)
        {
            //var petitions = new List<RegistrationPetition>();

            foreach (var a in ceremonyParticipations.Where(a => a.Petition))
            {
                // check for existing petition
                var noExistingPetition = !_registrationPetitionRepository.Queryable.Any(b => b.Ceremony == a.Ceremony && b.Registration.Student == registration.Student);
                // check for existing registration
                var noExistingParticipation = !_participationRepository.Queryable.Any(b => b.Ceremony == a.Ceremony && b.Registration.Student == registration.Student);

                if (noExistingPetition && noExistingParticipation && a.Ceremony.CanRegister())
                {
                    if (a.Tickets == 0)
                    {
                        modelState.AddModelError("Tickets", "You need to select more than 0 tickets.");
                    }

                    var petition = new RegistrationPetition(registration, a.Major, a.Ceremony, a.PetitionReason, a.CompletionTerm, a.Tickets);
                    petition.TransferUnitsFrom = string.IsNullOrEmpty(a.TransferCollege) ? null : a.TransferCollege;
                    petition.TransferUnits = string.IsNullOrEmpty(a.TransferUnits) ? null : a.TransferUnits;
                    petition.TicketDistributionMethod = a.TicketDistributionMethod;

                    registration.AddPetition(petition);
                }
            }

            //return petitions;
        }