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Extract the desired content from the file using "xmlstarlet" or "sed" or "awk" or some similar tool.
The process should refer the full name of the particular businessprocesses and then should just extract content in between that particular business process.

File from where the content to be extracted.

 <businessProcesses>
        <fullName>Customer Support</fullName>
        <description>Use for Customer Support, TDG and Port</description>
        <isActive>true</isActive>
        <values>
            <fullName>Action Item</fullName>
            <default>false</default>
        </values>
        <values>
            <fullName>Solved</fullName>
            <default>false</default>
        </values>
    </businessProcesses>
    <businessProcesses>
        <fullName>Customer Support - Port</fullName>
        <description>Telecom team use only</description>
        <isActive>true</isActive>
        <values>
            <fullName>New</fullName>
            <default>true</default>
        </values>
        <values>
            <fullName>Open</fullName>
            <default>false</default>
        </values>
    </businessProcesses>
</CustomObject>    

Required output.

<businessProcesses>
        <fullName>Customer Support - Port</fullName>
        <description>Telecom team use only</description>
        <isActive>true</isActive>
        <values>
            <fullName>New</fullName>
            <default>true</default>
        </values>
        <values>
            <fullName>Open</fullName>
            <default>false</default>
        </values>
    </businessProcesses> 

Assuming that the XML is well formed (the example lacks a CustomObject opening tag),

$ xmlstarlet sel -t -c '//businessProcesses[fullName="Customer Support - Port"]' -nl file.xml
<businessProcesses>
 <fullName>Customer Support - Port</fullName>
 <description>Telecom team use only</description>
 <isActive>true</isActive>
 <values>
 <fullName>New</fullName>
 <default>true</default>
 </values>
 <values>
 <fullName>Open</fullName>
 <default>false</default>
 </values>
 </businessProcesses>

This uses XMLStarlet with an XPATH query that extracts a copy of the businessProcesses node that has a fullName child node with the exact value Customer Support - Port.

The -nl at the end adds a newline to the output.

Don't compare XMLStarlet or any other parser of structured document formats with line-oriented text manipulation tools like sed, or awk.

You can get the desired output (with an extra space) with

awk 'NR==1 || (NR >= 15 && NR <= 26)'

or

sed -n '1p; 15,26p'

If you want a better answer, ask a better question.