Is it possible for a device to send an append to a Data File in Device Cloud? Are Device Cloud DataFiles immutable?

Testing Transport Wr21 and Digi Connect SP with the Serial to DC sample application. With each line of data sent to the Device Cloud it writes a new file adding an index number(test1.txt, test2.txt). If the device reboots the index resets and begins writing over critical data. Can I remove the index and append the file that was sent to the Cloud putting all my data in one file as it is sent one line at a time. I found this information referencing a Cloud Connector device that I believe is depreciated. Can a file already in the Device Cloud be appended?

Append data to an existing file in Device Cloud
view sourceprint?
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import com.etherios.connector.core.DataStream;
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// Path and name of the file to append the data in Device Cloud
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static final String DEST_PATH = “existingFile.txt”;
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CloudConnector connector = …;
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String dataToAppend = “This is the string text to be append.”;
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// Append to an existing file in Device Cloud the given string
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connector.appendDataToRemoteFile(dataToAppend, DEST_PATH);
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