Nav Data bases are coded according to a ARINC 424 spec. and use path terminators to do the coding. ie a heading to a altitude then turn etc. When you insert a waypoint you are only creating a direct segment. If you are flying a approach in nav then you should not modify a approach from the FAF inbound.

RNAV LEG TYPE DESCRIPTIONS.

a. Initial Fix (IF). This is the point or fix where a flight segment begins. An IF is not a route segment and does not define a desired track in and of itself. It is used in conjunction with other leg types such as a TF leg in order to define the desired segment.

Note: "IF" in this context is not to be confused with initial approach fix (IAF) or intermediate fix (IF); however, it may be located at one of these locations for coding purposes.
b. Track-to-Fix (TF) Leg. This designates a track or geodesic path between two fixes. If the TF leg is the first route segment of a flight path, the TF leg begins at an IF; otherwise, the first fix of the TF leg is the termination fix of the previous route segment. The TF leg is the primary straight route segment for RNAV.

c. Constant Radius to a Fix (RF) Leg. An RF leg defines a curved path route segment about a defined turn center that terminates at a fix. The RF leg begins at the termination fix of the previous route segment. The previous segment is tangent to the arc of the RF leg at that fix. An RF leg is the primary curved path route segment for RNAV RNP procedures. Waypoints defining the beginning and end point of the RF turn must be designated as “Fly-by.”

d. Course-to-Altitude (CA) Leg. The CA leg is used to code the initial leg at the beginning of the missed approach segment. This leg type requires a stated course and altitude at the beginning of the missed approach. This altitude will be the lowest of DA, MDA, or 400-ft above airport elevation (for helicopter point-in-space procedures, use lowest DA or MDA). A DF leg must always follow a CA leg.

e. Direct-to-Fix (DF) Leg. A DF leg is used to define a route segment (geodesic path) that begins at an aircraft present position, or unspecified position, and extends to a specified fix.

f. Heading-to-an-Altitude (VA) Leg. The VA leg is used in a departure route segment where a heading rather than a track has been specified for climb. The VA segment terminates at a specified altitude without a terminating position defined.

g. Course-to-Fix (CF) Leg. The CF leg is defined as a magnetic course that terminates at a fix. Although the CF leg is used in many traditional approach and departure procedures, this leg type is to be avoided in the design of RNAV procedures.

h. Vector-to-Fix (VM) Leg. A VM leg is used for whenever a departure route description specifies a course or heading to fly in expectation of a radar vector.

i. Vector-to-Intercept (VI) Leg. A VI leg defines a specified heading to intercept the subsequent leg at an unspecified position.