Tower FLM reported a NMAC.

Narrative

Aircraft X was in an RNAV approach to Runway 16L. An Unknown VFR aircraft [Aircraft Y] was in the pattern at 16X airport approx. 5 miles north of AFW airport. 16X VFR pattern is east of 16X airport which puts aircraft in line with our final approach course. Aircraft X was descending and the conflict alert sounded for Aircraft X and the VFR traffic. Traffic was called. Aircraft Z was about 5 miles in trail of Aircraft X and also conflicted with the unknown VFR traffic. Aircraft Z was head on to the VFR traffic. Aircraft Z was at 026 and descending the VFR was at 017 unverified. And a traffic alert was issued. The Targets appeared to pass directly over each other. The pattern at 16X should be west of that airport to keep traffic clear of AFW's Final Approach Course. This area 5 miles north of AFW continues to be an issue with VFR traffic that is not in communication with AFW tower or D10 Approach. Traffic conflict continue to increase. This is issue causes additional work load for AFW and D10 controllers on top of being a dangerous situation. AFW's class D airspace should be extended so that aircraft in this area will have to contact Tower. Or lower the class B shelf so that aircraft will be in contact with D10.