This is an issue of some debate, the short answer is don't, just change the profile of an existing material and hope this will get fixed in the future.
Previously Cura sent all the material profiles to your printer This was disabled by firmware because this could break firmware by setting the printing temperature to something unmanageable, after which people could no longer do an XY calibration print since that uses those temperatures, which by default works fine.
Anyway your new material now has a unique ID (UUID aka GUID) that the printer does not know.
If you set your printer to devel