Re: Carpentry question about Porch Columns
It's very possible to patch the post with a dutchman. It would be preferable to put in a temporary support so the work could be done on a bench, but a decent repair should be possible _in situ_.
You would need to specify a decent exterior wood such as Spanish Cedar to make the labor for this repair worth it; use a big-box store lumber and the repair may not last very long. Prime all ends; use an epoxy glue for the dutchman.
Remove not the ancient landmark, which your fathers have set.