You can find the point of intersection between two lines defined from existing points. After an intersection is found, you can save it by specifying a new point number.
To create a Line/Line intersection in the Survey Command Window
To create a Line/Line intersection, using the survey command language
LNLN [point 1] [point 2] [offset 1] [point 3] [point 4] [offset 2]
NE 1 100 100
NE 2 200 200
NE 3 175 200
NE 4 100 200
LNLN 1 2 100 3 4 -100
! INTERSECTION # 1 NORTH:158.578644 EAST:300.000000
An intersection is located between a line drawn between points 1 and 2 with an offset of 100 feet to the right and a line drawn between points 3 and 4 with an offset of 100 feet to the left.