Greetings,
If it doesn't matter how you arrive at the result - here is a workflow.
1. Convert points to raster.
2. Interpolate a surface from the points. Snap the result to raster from step 1. (same extent and cell size also)
3. Write a conditional statement that says where raster 1 is null, replace it with raster 2. Where it is not null, keep raster 1.
Regards,
Eric