I'm glad i titled this part as fairly advanced ;)

Sheet cam can't isolate parts of paths, only complete entities.

I have taken all the 3mm holes off the job now and will use a steel drilling jig to drill them as a second op, five of them must match up with another part that is drilled and tapped edge-on a strip of 5mm alu so this part must be jig-drilled and to make sure holes match both parts get jig drilled.

That also speeds up the time on the mill.

It seems i have 3 options now,

1 - remove the loops at the ends of the slots and jig-drill after, cutting just a straight slot

2 - as suggested, create a duplicate part of just that area and cut between roughing and finish passes.

3 - Create a new layer and put three straight slots and smaller loops on the ends on it and cut that between rough and finish passes, allowing the finish pass to take the loops to final size.

I think I would try opt 3 as a first go, seems to make most sense to me - 3 short slots opposed to a larger path.