Hi, Elaine. I think that you will have all kind of problems trying to put stain over the grease. I would scrape up all the grease that you can, wash with Tri-Sodium Phosphate, let it dry after rinsing and sand any of the area that was wet. You do not have to machine sand. Going over the area hand sanding or with a finishing sander or random orbital sander using the same grit that you used for the machine sanding should do it.