Taken from my Ma's recipe book.......
( Take a bushell of apples, cut them up or pound them, place in a large tub. When they start to ferment add some water which they will absorb. Keep adding water every day until they absorb no more.
Leave, covered for a month, strain liqour off the pulp. To every gallon of liqour add half a pint of vinegar, hot that has been boiled and reduced from one pint. Leave for six weeks and bottle.)
From this, and Mother made it every year as I remember, I would say that the reduced vinegar (malt or cider, definately not acetic acid) would take the place of the "mother" Hope that helps