var someVariable = MainMethodToCall(rowId)

public ICollection<RowObject> MainMethodToCall(int rowId)
{
 ICollection<RowObject> rowsCollection = new Collection<RowObject>();
rowsCollection = GetChildRows(rowId,rowsCollection);
return rowsCollection;
}

public ICollection<RowObject> GetChildRows(int rowId, ICollection<RowObject> rowsCollection) {
        var rowObject= DatabaseCall.GetRowObject();
        rowsCollection.Add(position);
        if (DatabsaeCall().Where(x => x.ParentRowId == rowId).Any())
        {
            var childRows = DatabaseCall().Where(x => x.ParentRowId == rowId);
            foreach (var childRow in childRows )
            {
                GetChildRows(childRow.Id, rowsCollection);
            }
        }
        return rowsCollection;