Код ниже объединяет членов каждой записи по имени записи
import xml.etree.ElementTree as ET
import pprint
XML = '''
<address-group>
<entry name="TBR1">
<static>
<member>TBR1-1.1.1.1_21</member>
<member>TBR2-2.2.2.2_24</member>
<member>TBR3-3.3.3.3_21</member>
<member>TBR4-4.4.4.4_24</member>
</static>
</entry>
<entry name="TBR2">
<static>
<member>TBR1-4.1.1.1_21</member>
<member>TBR2-4.2.2.2_24</member>
<member>TBR3-4.3.3.3_21</member>
<member>TBR4-9.4.4.4_24</member>
</static>
</entry>
</address-group>'''
root = ET.fromstring(XML)
data_by_entry = {}
entries = root.findall('.//entry')
for entry in entries:
data_by_entry[entry.attrib['name']] = [m.text for m in entry.findall('./static/member')]
pprint.pprint(data_by_entry)
output
{'TBR1': ['TBR1-1.1.1.1_21',
'TBR2-2.2.2.2_24',
'TBR3-3.3.3.3_21',
'TBR4-4.4.4.4_24'],
'TBR2': ['TBR1-4.1.1.1_21',
'TBR2-4.2.2.2_24',
'TBR3-4.3.3.3_21',
'TBR4-9.4.4.4_24']}