D.G.
I would say no because if you feed directly from the jar every time you stick that spoon into the jar from the babies mouth you are contaminating it with her saliva.Baby food is very reasonably priced and a small waste should not be such a big deal.
My step Mother made my baby sisters food in a food processor and froze extras in ice cube trays and then put in freezer bags, she always had chemical and sugar free food and it had real taste as herbs were used to help flavor it.She was rarely ever ill growing up.