Be able to add a seat to a row of a ticketed event without redoing the whole seating chart/venue

We want to be able to add a seat to a row of a ticketed event without redoing the whole seating chart/venue. It would also be nice to have the option to amend the seating chart/venue after ticket sales have started as we needed additional wheelchair acessible space and wanted to be able to add a ticket/"seat" for that space. Thank you!