HELP boy names

This is my 3rd boy and I'm completely stuck on names... I have the name Kaizen in mind but don't feel it fits with his brothers names.. Im not a fan of weird miss spelt names but I also would like to keep two middle names first one with double l's and the second to start with a J. For the first name I was thinking something that starts with a K but open to anything at this point

Oldest - Seth William John

Middle - Mason Mitchell James

Youngest - HELP NEED BAD

Last name is MacDonald for the oldest boys but plan on changing to dad's last name once married his last name is Bent