Ralph, Doug again. Been thinking about your solution. It may not be the quickest way, but perhaps a solid installation. I have to deal with the radius in the existing hole corners. Perhaps I could do as you suggest and cut my step the same all the way around, square the corners, then fill in. I have some HDP scrap that is white like the laminate top. Do you think that might be to soft of material to use? Hardwood would probably be better. More thought for sure. Thanks for the tips. Any more would be welcome.
I'm not familiar with the characteristics of HDP (High Density Polyethylene?), but for the relatively narrow strips you'd be using, it might be OK. Glue may be an issue, though, since many such materials require special adhesives. One likely advantage would be dimensional stability. With hardwood, there will be seasonal expansion/contraction to consider. Not much, since the pieces would be small, but it will still be there.
I'm guessing the substrat of the existing top is MDF, with the laminate applied with contact cement. Thus, the existing top would be dimensionally stable.
Other options would include:
1. strip the laminate from the top, resize the hole with MDF pieces, and then re-laminate the top, or
2. build a new top with the required hole size.
Ultimately, #2 above may actually be the least trouble.