It is fraught with disaster to try to input your own waypint data and/or procedures. Within the navdatabase, you could override the existing data, or worse over-ride an existing waypoint with your custom data.
There is significant coding that goes into a waypoint, and this all predicts the performance..The user has no way to input flyover or flyby, speed restrictions, at or above, or other data that significantly affects how the aircraft will perform.
I know of at least one incident, where as soon as the ac crossed the waypoint, the ac porpoised down the the MDA before the operator could react.
Dont get caught with anything in the box that was generated by your navdatabase provider.
Ask them to back that up by reference to the Regulations!
Here are the regulations that specifically and otherwise prohibit an operator from entering their own IFR waypoints.
ICAO Annex 15, Doc 8126
RTCA ED-76, ED77, DO-200A, DO-201A
ARINC 424
FAA AC20-DB