Pardon me, but I am not satisfied with the responses.
I am proceeding direct to waypoint ABC which is 300 NM in front of me. I decide to create a new waypoint which will be ABC -100NM. I open the FIX INFO page. I type in ABC and 100 in radius. I select 4L which drops the radius into FPLN. That radius fix remains dynamic until I select heading.(does it not?) I select heading, insert, then select NAV. I can do that in one second, yet I still get a wiggle.