awk '

#
# DCDB
#

/^<DCDBEntry / {
   split($0, dcdb, /"/);
   sub(/ *$/, "", dcdb[2]);
   Folder[dcdb[2]] = dcdb[4];
       Tz[dcdb[2]] = dcdb[6];
   next;
}

#
# LDS
#

/^<LDSEntry / {
   split($0, lds, /[":]/);
   folder = lds[2];
   tz     = lds[6];
   SiteUnit[folder, tz] = lds[3];
     Device[folder, tz] = lds[4];
   next;
}

#
# Input
#

/^</ {
   next;
}

FNR==1 {
   print $0, "Folder", "SU", "Dev";
   next;
}

{
   dcdb_in = $2;
   folder = Folder[dcdb_in];
   tz     =     Tz[dcdb_in];
   su     = SiteUnit[folder, tz];
   dev    =   Device[folder, tz];
   print $0, (folder ? folder : "?"), (su ? su : "?"), (dev ? dev : "?");
   next;
}

' DCDB.xml LDS-*.xml inputfile

> cat DCDB.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<DCDBTable>
<DCDBEntry DCDB="0862976 " folder="768678" timeZone="2"/>
<DCDBEntry DCDB="0911297 " folder="975426" timeZone="1"/>
<DCDBEntry DCDB="0201347 " folder="1389781" timeZone="2"/>
<DCDBEntry DCDB="0800659 " folder="2035595" timeZone="4"/>
<DCDBEntry DCDB="0123033 " folder="2143699" timeZone="2"/>
<DCDBEntry DCDB="0911515 " folder="2315643" timeZone="1"/>
<DCDBEntry DCDB="0123913 " folder="2367867" timeZone="2"/>
<DCDBEntry DCDB="0713934 " folder="2407712" timeZone="5"/>
</DCDBTable>

> cat LDS-*.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<LDSMappingTable>
<LDSEntry LDSKey="3351216:1:TV" LDSValue="7"/>
<LDSEntry LDSKey="1389781:1:VCR1" LDSValue="2"/>
<LDSEntry LDSKey="3351216:2:TV" LDSValue="2"/>
<LDSEntry LDSKey="3351216:3:TV" LDSValue="6"/>
<LDSEntry LDSKey="3351511:1:TV" LDSValue="10"/>
<LDSEntry LDSKey="3351511:1:VCR1" LDSValue="11"/>
<LDSEntry LDSKey="3351511:2:TV" LDSValue="4"/>
<LDSEntry LDSKey="3351511:2:VCR1" LDSValue="5"/>
</LDSMappingTable>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<LDSMappingTable>
<LDSEntry LDSKey="3351217:1:XTV" LDSValue="7"/>
<LDSEntry LDSKey="1389782:1:XVCR1" LDSValue="2"/>
<LDSEntry LDSKey="3351217:2:XTV" LDSValue="2"/>
<LDSEntry LDSKey="3351217:3:XTV" LDSValue="6"/>
<LDSEntry LDSKey="3351512:1:XTV" LDSValue="10"/>
<LDSEntry LDSKey="3351512:1:XVCR1" LDSValue="11"/>
<LDSEntry LDSKey="3351512:2:XTV" LDSValue="4"/>
<LDSEntry LDSKey="3351512:2:XVCR1" LDSValue="5"/>
</LDSMappingTable>

> cat inputfile
1DATE HHIDLDS BothOff 91 NG A=D 90faulRoundOnOff OffOn OthersMATCHED NOMATCH MATCH%
0721 0201136 1 544 . . . 1 . . . 895 1 99.89
0721 0201347 1 1296 . . . . . . . 144 . 100.0
0721 0201347 2 818 . . . . . . . 622 . 100.0
0721 0201364 1 1123 . . . . . . . 317 . 100.0
0721 0201364 2 1327 . . . . . . . 113 . 100.0

1DATE HHIDLDS BothOff 91 NG A=D 90faulRoundOnOff OffOn OthersMATCHED NOMATCH MATCH% Folder SU Dev
0721 0201136 1 544 . . . 1 . . . 895 1 99.89 ? ? ?
0721 0201347 1 1296 . . . . . . . 144 . 100.0 1389781 1 VCR1
0721 0201347 2 818 . . . . . . . 622 . 100.0 1389781 1 VCR1
0721 0201364 1 1123 . . . . . . . 317 . 100.0 ? ? ?
0721 0201364 2 1327 . . . . . . . 113 . 100.0 ? ? ?