So, you want to remove existing tin nodes (lidar points) from within a given distance of your surveyed point shots before inserting those point shots?
Are point shots that comprise a single cross section closely and/or relatively evenly spaced?
Are they closely spaced relative to the distance between cross sections?
Are they ordered along the line from beginning to end or at least distinguishable (e..g., using some form of attribution or placed in separate files) from points that belong to other cross sections?
Are cross sections relatively straight in XY?
Would it be beneficial to turn those points into lines and insert them as breaklines?