How to merge XML string with XML created by objectify?

I am using python 2.7

I currently have a procedure in place that generates orders in XML from csv data that works. However everything is hardcoded, and I want to make it a bit more dynamic as I expand the code to fit more clients.

As it stands, I have a section that adds basic info such as ship to and bill to address to the order

from lxml import objectify
E = objectify.E
fileElem = E.request(
    E.customerID("###"),
    E.userID("####"),
    E.btNameCompany("BillToCompany"),
    E.btAttention("John Snow"),
    E.btStreet("123 Any Street"),
    E.btAddress2(),
    E.btAddress3(),
    E.btCity("City"),
    E.btState("State"),
    E.btZip("12345"),
    E.btCountry("USA"),
    E.btTelephone(),
    E.btEmail(),
    E.customerPO(customerPO),
    E.stNameCompany(shipToCompany),
    E.stAttention(shipToAttn),
    E.stStreet(shipToAddr),
    E.stAddress2(shipToAddr2),
    E.stCity(shipToCity),
    E.stState(shipToState),
    E.stZip(shipToZip),
    E.stCountry(shipToCountry),
    E.shipMethod("FedEx Ground"),
    E.stTelephone(shipToPhone),
    E.shipNotificationEmail(shipToEmail),
    E.shipperID("ShipperCompanyID"),
    E.messages(),
    )

From there I've been appending product info by calling a function that returns a product built the same way, with hardcoded tags.

def getProductXML(sku, qty):
    productList = {"Company Brochure":
       E.item(
           E.quantity(qty),
           E.productID("ID #"),
           E.productDesc("Description")
              ),
      "Company Product":
       E.item(
           E.quantity(qty),
           E.productID("ID #"),
           E.productDesc("Description")
              ),}
     return productList[sku]


fileElem.append(getProductXML(sku, qty))

I've made some adjustments that allows me to add whatever tags a particular item needs by setting up an excel file. Each item occupies two rows. One row is tags, the other row is content, with a sku in the first column as an identifier.

sku    |    qty    |    product ID    |    random attribu    |    random attribu2
sku    |    1      |     thing1       |    English           |     z fold

So I have added a bit of code that runs through the excel document and generates XML as string. I chose to create a string because running a loop within objectify caused errors. I was also not able to use variables as the tags, so if variable = "quantity", E.variable(qty) becomes qty rather than qty.

from lxml import etree as ET
def GetItemXML(sku,qty)

    def HeaderRows(r_sheet, rows, cols ):
        headerRows = {}
        for row in range(0,rows):

            if row%2 == 0:
                headerRow = []
                for col in range(0,cols):
                    if col == 0:
                        thecell=r_sheet.cell(row-1,col)
                        headerSKU = str(thecell.value)


                    else:
                        thecell=r_sheet.cell(row,col)
                        header = str(thecell.value)
                        headerRow.append(header)

                headerRows[headerSKU] = headerRow

            else: continue

        return headerRows



    def ContentRows(r_sheet, rows, cols ):
        contentRows = {}
        for row in range(0,rows):
            if row%2 == 1:
                contentRow = []
                for col in range(0,cols):
                    if col == 0:
                        thecell=r_sheet.cell(row,col)
                        contentSKU = str(thecell.value)


                    else:
                        thecell=r_sheet.cell(row,col)
                        content = str(thecell.value)
                        contentRow.append(content)

                contentRows[contentSKU] = contentRow
    ##            print contentSKU


            else: continue
        return contentRows

    def getItemXML(sku, qty, contentRows, headerRows):
        skuExists = True

        string = ""
        ##################################### INSERT LOGIC TO ADD PROPER PRICING, QTY, AND SHIPPING WEIGHT BASED ON QTY ENTERED  ####################################
        try:
            columnIndex = 0
            for column in headerRows[sku]:
                string = string + ET.tostring(E(column, contentRows[sku][columnIndex]))
                columnIndex +=1
        except: skuExists = False

        return string, skuExists

This outputs the following string

'<quantity>1</quantity><numPages>1</numPages><padding>0</padding><versions>0</versions><price>$$.$$</price><productID>ProdID#</productID><productDesc>Product Description</productDesc><device>0</device><inksF>4</inksF><inksB>0</inksB><runW>##.00000</runW><runH>##.00000</runH><cutW>##.00000</cutW><cutH>##.00000</cutH><productType>Inventory</productType><coatingID>0</coatingID><foldingID></foldingID><scoreID>0</scoreID><bindID>0</bindID><proofID>0</proofID><mailID>0</mailID><listID>0</listID><customerDataListID>0</customerDataListID><note></note><memo></memo><weight>16.0</weight><isCanvas></isCanvas><artID>28933</artID><mapingID>0</mapingID><customerApproval>accepted</customerApproval>'

However I cannot turn this string back into XML

>>> root = objectify.fromstring(string)

Traceback (most recent call last):
  File "<pyshell#15>", line 1, in <module>
    root = objectify.fromstring(string)
  File "lxml.objectify.pyx", line 1802, in lxml.objectify.fromstring (src/lxml/lxml.objectify.c:22312)
  File "lxml.etree.pyx", line 3032, in lxml.etree.fromstring (src/lxml/lxml.etree.c:68292)
  File "parser.pxi", line 1786, in lxml.etree._parseMemoryDocument (src/lxml/lxml.etree.c:102641)
  File "parser.pxi", line 1674, in lxml.etree._parseDoc (src/lxml/lxml.etree.c:101470)
  File "parser.pxi", line 1074, in lxml.etree._BaseParser._parseDoc (src/lxml/lxml.etree.c:96652)
  File "parser.pxi", line 582, in lxml.etree._ParserContext._handleParseResultDoc (src/lxml/lxml.etree.c:91461)
  File "parser.pxi", line 683, in lxml.etree._handleParseResult (src/lxml/lxml.etree.c:92647)
  File "parser.pxi", line 622, in lxml.etree._raiseParseError (src/lxml/lxml.etree.c:91943)
XMLSyntaxError: Extra content at the end of the document, line 1, column 14
>>> 

OR

>>> ET.XML(string)

Traceback (most recent call last):
  File "<pyshell#12>", line 1, in <module>
    ET.XML(string)
  File "lxml.etree.pyx", line 3012, in lxml.etree.XML (src/lxml/lxml.etree.c:68047)
  File "parser.pxi", line 1786, in lxml.etree._parseMemoryDocument (src/lxml/lxml.etree.c:102641)
  File "parser.pxi", line 1674, in lxml.etree._parseDoc (src/lxml/lxml.etree.c:101470)
  File "parser.pxi", line 1074, in lxml.etree._BaseParser._parseDoc (src/lxml/lxml.etree.c:96652)
  File "parser.pxi", line 582, in lxml.etree._ParserContext._handleParseResultDoc (src/lxml/lxml.etree.c:91461)
  File "parser.pxi", line 683, in lxml.etree._handleParseResult (src/lxml/lxml.etree.c:92647)
  File "parser.pxi", line 622, in lxml.etree._raiseParseError (src/lxml/lxml.etree.c:91943)
XMLSyntaxError: Extra content at the end of the document, line 1, column 14

Can someone please recommend a way to combine the xml in string form with the xml I am generating through objectify?

Thank you.