CPack create packages with executables from different source tree - cmake

Question

The problem is as follows:
Project structure:
ProjectDir
- CMakeLists.txt
- src
-- CMakeLists.txt
-- FirstApp
--- CMakeLists.txt
--- ... sources ...
-- SecondApp
--- CMakeLists.txt
--- ... sources ...
- tools
-- CMakeLists.txt
-- SomeTool
--- CMakeLists.txt
--- ... sources ...
-- SomeOtherTool
--- CMakeLists.txt
--- ... sources ...
What I want to achieve is:
package (let it be rpm or deb) with SomeTool binaries;
package with FirstApp, SecondApp AND SomeOtherTool binaries;
As far as I know:
CPack is putting into packages content the stuff that is defined in install command;
CPack cannot be called ( include(CPack) ) twice in the same tree (for example it cannot be called in CMakeLists.txt at src level AND SecondApp level);
What do I have
In ProjectDir/tools/SomeTool/CMakeLists.txt I've (it's pseado code):
PROJECT( SomeTool )
SET(TARGET SomeTool)
SET(CPACK_GENERATOR "RPM")
SET(CPACK_PACKAGE_NAME "SomeTool")
# ...
# all the other CPACK_* stuff
# ...
include(CPack)
add_custom_target(${TARGET}-package
COMMAND cpack --config "${CMAKE_CURRENT_BINARY_DIR}/CPack${PROJECT_NAME}Config.cmake")
SET(SOURCES ...)
SET(HEADERS ...)
add_executable(${TARGET} ${SOURCES} ${HEADERS})
install(TARGETS ${TARGET}
RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}/usr/bin)
This way I can call make SomeTool-package and it'll create package (SomeTool.rpm) with content /usr/bin/SomeTool. Great!
I can have very similar CMakeLists.txt in ProjectDir/src/ dir:
# src/CMakeLists.txt
PROJECT( MainProject )
SET(CPACK_GENERATOR "RPM")
SET(CPACK_PACKAGE_NAME "MainProject")
# ...
# all the other CPACK_* stuff
# ...
include(CPack)
add_custom_target(MainProject-package
COMMAND cpack --config "${CMAKE_CURRENT_BINARY_DIR}/CPack${PROJECT_NAME}Config.cmake")
add_subdirectory(FirstApp)
add_subdirectory(SecondApp)
# src/FirstApp/CMakeLists.txt
SET(TARGET FirstApp)
SET(SOURCES ...)
SET(HEADERS ...)
add_executable(${TARGET} ${SOURCES} ${HEADERS})
install(TARGETS ${TARGET}
RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}/usr/bin)
# src/SecondApp/CMakeLists.txt
SET(TARGET SecondApp)
SET(SOURCES ...)
SET(HEADERS ...)
add_executable(${TARGET} ${SOURCES} ${HEADERS})
install(TARGETS ${TARGET}
RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}/usr/bin)
This way I can call make MainProject-package and it'll create package (MainProject.rpm) with content /usr/bin/FirstApp and /usr/bin/SecondApp. Great!
SomeOtherTool also have a CMakeLists.txt which looks the same as FirstApp and SecondApp CMakeLists.txt and I can call make SomeOtherTool and it'll produce SomeOtherTool binaries.
The Question
As CPack is puting into packages stuff connected to install command, how can I connect SomeOtherTool with my MainProject-package ?
My solution would (is) be to put another install clause at the end of src/CMakeLists.txt that'd look like:
add_dependency(MainProject SomeOtherTool)
install(FILES ${CMAKE_BINARY_DIR}/SomeOtherTool DESTINATION ${CMAKE_INSTALL_PREFIX}/usr/bin )
Is there any other way? This solution doesn't look clean.. If I change the SomeOtherTool executable name I'll have to change it in here also. The same goes with install path.