Identify the parts in the assemblied

At the top of the model tree, enter text (part number) in the filter and the tree will be reduced to anything the matches with the assembly structure.

Presumably you are not using Windchill. From what I understand this might be something that Windchill handles for you.

If you're trying to find all the assemblies in a Windows directory (and its subdirectories) that use a particular part or assembly, you can take advantage of the fact that a part name is stored in the assembly file. I wrote a batch program to find these kinds of things a while ago. It's run in a command window. It's not very fast, but has helped me a lot.

::
:: Builds a list in a file with the complete filenames of any assembly that
:: contains the expression specified.
::
:: Usage: whereused target [filename]
:: target = the target string to search for
:: filename = optional output file name. If no name is
:: provided, the default "results.txt" will
:: be used.
::
:: Note: If the output file already exists, any new results are appended to
:: the end of the file. In this way, a batch file could be used to find
:: a number of parts and save all the results in a conglomerated report.
::
:: Author: Kenneth J. Farley
:: Date: 02 July 2015
::

@ECHO OFF

::
:: Check that at least one argument has been provided. If not, issue a
:: "Usage" message and exit.
::

if NOT "%~1"=="" (goto :doSearch)
echo Usage: whereused target [filename]
echo target = the target string to search for
echo filename = optional output file name
exit /b

::
:: Do the initial setup stuff for the run.
:: * Save the input string to a variable.
:: * Write the search string and some delimiter characters to the results file.
:: * Trigger a search of all subdirectories.
::

:doSearch
set strSrch=%1
set "fileRes=%CD%\results.txt"
if NOT "%~2"=="" (set "fileRes=%CD%\%2")
echo Saving to "%fileRes%"
if NOT exist %fileRes% echo. > "%fileRes%"
echo ------ %strSrch% ---------------- >> "%fileRes%"
echo. >> "%fileRes%"
for /r /d %%d in ("*") do call :doDir "%%d"
echo. >> "%fileRes%"
exit /b

::
:: Using the directory stack, changes to the target directory. Checks to see
:: if there are any assembly files and if so, processes them. Once done,
:: "pops" back to the original directory.
::

:doDir
pushd %1
set dirName=%1
if exist *.asm.* (call :doCheck)
popd
exit /b

::
:: Performs the searching operation and outputs any positive results to the
:: output file.
::

:doCheck
echo Checking %dirName%
for /f %%a in ('findstr /I /M %strSrch% *.asm.*') do echo %dirName% : %%a >> "%fileRes%"
exit /b

Hopefully it'll be useful.

Creo part files do not contain any information about what assemblies they are used in. I suppose the exception to this is if a part has some sort of reference to the assembly (parent-child type reference).

Windchill keeps full track of where parts are used, if you are using it. 

This is how I find them, but I get some false positives:

I click on the cmd window and then type:

whereused partnamehere (where partnamehere is the file name that you are checking - i.e. 1201_1003 for 1201_1003.prt or .asm

At the end it opens up a .txt file and I check each file to verify where the part is used in the file. This bring in all upper level assemblies all the way to the top level.

Tedious, but has helped me a lot. Especially when obsoleting a part.

No windchill.