As far as Project Requests go via the API, there are only endpoints for creating a request and for submitting one for review. We don't have an Edit/Update endpoint for them. Even within the interface of TDNext or TDAdmin there isn't a mass update feature for these unfortunately.
Possibly for a service the technical services team could modify them for you, but you would want to put in either a VAS request if you have purchased VAS hours, or else a Support ticket that might end up needing to go to your sales consultant to determine if such a request would require any sort of charge for the effort to fulfil it.
Sr Support Consultant, CS