My client wants to add an Option A quote to an existing Option E contract without changing the Option A price, at first glance I think this is bad practice and should not be permitted, however is it permitted under the NEC rules?
It is not part of the contract but like most things anything is possible by agreement. If there is a specific element of work that you agree you will do for a fixed sum and you mutually agree that in writing and they they will pay you that sum as a fixed price then I do not see that as a big problem. I emphasise if both Parties agree - as this is outside of the option E rules so not something that can be forced.